1. Do I hang three separate curtain rods or find something custom to do a single rod all the way across? (Would need to be over 12 feet long if just one rod, which seems excessive to me- but I'm no pro!)

Three separate curtain rods.*

2. What height do I hang the rod?

Read this.

FYI- this room is on the front of the house along with office and formal living, so wasn't sure if curtains in all rooms needed to be the same/similar to avoid looking funky from outside.

The curtains don’t need to be the same fabric. Just make sure they’re all lined the same.

*Edit: I’ve changed my mind based on Mrs. S’s suggestion: One rod with panels between each window.

Yes...the lining should be the same.

I could see plantation shutters as another option for those windows.

On the curtain and rod, I would hang the rod right about where you have the line. Hang one long rod. I do things on a bit of a budget, and on a similar panel of windows, I bought 2 long rods from Bed Bath&Beyond a few years ago, and you can attach them together with a special screw that has threads on both ends. You will of course have to figure out the supports, between the windows. (or maybe you're not on such a strict budget, and can look at custom). So, I would have curtain panels on each end, and also between the windows.

I'll let others help you with pattern/color. I like neutral curtains (as you have chosen), but there's lots of room for color in your lovely space. In terms of length, curtains are easily hemmed to skim the floor. If I can do it, so can you. Also, there's iron on tape specially made for hems, just in case you can't sew (I can't either, but mom threads the sewing machine and I try to go in a straight line, lol). Your curtains will look the same-ish from the outside because (a) you have white blinds (very nice), and (b) you can get curtains with white lining on the backside for that purpose.

For the fireplace, I need to mention that TVs above fireplace aren't a great solution. Is that temporary? TVs are best viewed at eye level height when you are sitting down. You have all those other walls--can you move the TV?

Overall, it's a lovely space, and I would like to see your follow up pictures when you're done with the curtains!

1 rod (6 panels) but I would hang it at the bottom edge of the crown molding. Fabric same color as walls or the white of the woodwork. Bring the blue of the rug up into 3 places in the room i.e. pillows, art, lamps

Two things I notice, weird short chunk of crown molding on either side of windows. My eye is drawn to it and not in a good way. Also if you remove it, you can extend your rods. But I would not do fabric panels on those windows. i would do fixed roman shade.
And linen fabric stretches/relaxes.....a lot. I would advise against using linen for a panel unless you are using fabric that is not truly linen.

@ mrs. S: Thanks so much for your response-- very helpful.

We are definitely on a "budget" as we are trying to furnish this house, finish the basement and make a few other modifications, but can save for a bit to do it right if needed. Additionally, both my mom and MIL can sew (and I can do hem tape-ha!)

As far as doing one rod with panels between all the windows--should the panels cover the entire wall space between windows? I've seen it done that way when the windows are pretty close together, but never paid attention in situations like mine with several feet between windows.

As for the TV height-- it really is one of the only things hubby requested. so I let him have it. I'm not a huge TV person in general, but he is, and I have quite a few other "me" spaces to control (office, since I work from home; formal living, sunroom, etc) I should mention that the wall with the arched mirror we plan to open up later this year with either French doors or a cased opening as our sunroom is opposite that wall and very under utilized with it's current access, so that leaves the fireplace wall and wall opposite fireplace as possibilities for TV wall. I will ask him, but not sure it bothers me enough to press the issue with him.

"As far as doing one rod with panels between all the windows--should the panels cover the entire wall space between windows?"

Yes.

@typeandrun: YES!! I think that molding is SO weird right there. The opposite wall has molding all the way across (which kind of helps balance, I guess?)- but I think its strange since its not all the way around. How much work would it be for hubby to take that down and fix the drywall?

also the panels I have in mind are a poly/linen blend--so the wrinkle and stretching properties aren't really the issue more of an issue to pick the right color/texture for the room.

@Judy G- since putting it up around the room is not an option because of roof line- should I take down and try to repair now? This home was built in the 1990's and updated just before we purchased. They made mostly good choices, but this one baffled me. Should I consider doing some sort of ceiling beams in the future or just leave it plain?

@adparker53, not knowing what is under molding but most likely drywall was finished then molding added. Hopefully drywall patching, prime and paint touch up

Have your carpenter do a faux molding cornice to hide the drapery hardware and have it pick up where the current molding on both sides ends. And I would do one long rod with panels set in between all the windows. Here are a couple of examples so you see what I mean:

@Sabrina Alfin Interiors- that is beautiful, but probably above my current budget. I would definitely consider saving for it, though. Any rough estimate on cost of carpentry for something like that?

I really couldn't say; labor and material costs vary so widely around the country. The materials for the cornice won't be much; but the labor for installing and painting it is probably where most of the cost lies. I'd advise getting a few quotes. ETA: it's possible your window treatment fabricator can do this for you as part of the cost for the curtain panels and installation. You should ask, and bring these photos with you.

@Mrs. S-thanks for the visuals- very helpful and more budget friendly. As far as the molding---it is open on the top. It looks like they designed it to do some sort of up-lighting in the molding (which was sort of common in my area in the 90's/2000's I guess) but then never did the lighting in it. Which honestly I'm thankful for-but I don't care for that and would never have used it.

I like what Mrs. S proposes better than what I said originally, which is to do one rod vs three.

I'm adding a pic of our master bedroom because honestly it's got the same issues. The molding on some walls but not all and multiple spaced windows. Sounds like consensus is single rod with curtains covering space between. That work here too?

I think the windows are too far apart for a single rod. But IMO they are close enough that rods over each window and panels will look odd. I'd go with a roman shade

I think there's definitely room for different options here. So, agreeing with the others.

Here's a nice option to make use of the larger wall space between the windows.

Somewhat off topic, you have a very nice living room, and I agree with removing those structures at each side of the fireplace. I would probably put bookcases there, although they don't have to be tall. Large paintings above them or gallery walls would take away the emphasis from the functional TV. I would remove everything off the mantel. I notice that your rug is really too small for the space, and a larger and more colorful one, perhaps an Oriental, would make a much greater statement and brighten this room considerably. You can pull in the colors from the rug for the art and other accessories. Your rooms seem very monochromatic and you may prefer that, but color is coming back in a big way in home decoration, and I think it actually makes people feel better when everything is not gray or beige, and they're surrounded by pretty colors. I would pick a carpet that has some warm colors, in addition to cooler colors, to give the room some depth.

@Ingrid: thank you- any other thoughts on items next to fire place? like an certain look/item you have in mind? Everything I seem to put there just looks funny and the wall is far to big to just be bare. I do have a chase lounger that matches this room pretty well that I'm considering putting in the corner of the room to the left of fireplace. not sure what that does to balance the room though. If I put the chase on left, I probably not place anything else over on that side and may just need something else to the right of fire place. I do agree on it looking a bit monochromatic---but I seem to always pick blues, grays and tans...for everything. That rug is a 10x13 believe it or not and I just don't have a budget at the moment to purchase a new one, so it will have to hang on for awhile, but I think a 13x15 or larger could help, and would attempt to get out of my color funk and do something outside my box!

I know you said your husband mounted TV above mantle but it actually might work out better for viewing and you certainly have the space by placing it on a console to the right of the fireplace.