1. I've included a link so you have a visual of dark baseboards and painted window trim. I see no reason you can't paint only the window trim. If you decided to paint the baseboards then I'd go ahead and paint the door trim also. My house is all white trim & baseboards with stained pine doors so I know how great the look is! :~). 2. Your doors and trim may only need a good cleaning, a touch up with stain and then sealed. Replacing will be much more expensive and labor intensive than just painting. If you decide to paint them, talk to someone at a paint store (not a big box) and ask about the products they now have that you can use instead of sanding. If the surface has really shiny finish then you'll probably need to do some light sanding. Here is a link that might be useful: white trim, dark baseboards

Those pictures are of farmhouse style? Really? They look kind of froufrou to me, and in my book, farmhouses are simple, modest, utilitarian structures. But maybe now that traditional farms are pretty much dead, "farmhouse" is just another label for whatever some highly-paid interior designer thinks looks "traditional." I'm with the rest of the crew here. With 8' ceilings, that's no mansion you have there. Trying to make it look like one with fancy crown molding will just make it look like a parody of one. I say let your house be what its architect meant it to be. But that's just my opinion. It's your house, and if crown molding makes you happy, why not? I'd suggest the narrowest, simplest molding you can find. If the the next person who buys your house doesn't like it, they can always pry it off and patch the holes.

@millworkman ... I've tried posting a number of times with photos so I'm going to try them one at a time ..... Our house is completely gutted but I'll attach some pictures if helpful. I've ordered 2 panel raised smooth solid core doors (straight top). Our kitchen cabinets (raised straight panel) are being painted white and I've attached a picture of one of them along with sample of countertops. All the trim and doors and plantation shutters will be painted the same white that are on the main floor. Floors will be a medium brown 6 1/2" white oak engineered hardwood that will be throughout the main floor and up the stairs, hallway upstairs and master bedroom. Other bedrooms will be carpeted. The trim around the windows on the main floor will all be painted white where it's framed for the shutters. Other windows on the 2nd floor currently just have trim at the bottom and it would be nice to update. Looking at updating the stair spindles to possibly just straight squared or rounded wood vs the more colonial looking ones and painted white. Would like to be able to add some wainscoting in the entry and other areas down the road at some point. We've also taken off a lot of brick on our fireplace that had a crazy configuration and will be having a surround and mantle built for it.

We have an old house. Much of the trim didn't match between the old 1850ish and the addition of 1889. No one ever noticed. If the size of the 2 trims don't compliment each other, that would be more of a giveaway.