Thanks jejtvr. I'll try to answer your questions. I don't have a view of that side of the house. It's the side, not visible from the street. The house is a rectangle there with gables on each end. The dining room will tie in as in my drawing, and it will be the only dining area in the house. We have 2 kids, only one living at home, and in-laws live nearby. There will be windows on the other two sides of the dining room, just not the north end. I couldn't put windows on the west side of that 3d plan because they blocked the view into the house. I showed the best overall pictures of the interiors of the two rooms that will adjoin this dining room in the OP. I'm not totally convinced beadboard on the kitchen ceiling is the best idea either, but I have been unimpressed by the drywall work we've had done in the past on both the living room and kitchen, and can see joint lines that should be smooth. That's probably why they used that popcorn texture originally. It's so much easier to see things that don't work in the houses of other people, and I don't want to make this house so odd that it will be hard to sell down the line. I've seen other people, including my mother, do that to their homes, and they don't see it at all. After they've done it, there's not much you can say except "enjoy it". Meanwhile I'm thinking what a chore it's going to sell it and that it will probably fall on me to do it. I'd like the dining room and kitchen to get a "Wow! this is great" reaction from buyers, not a "Whoa! how much is it going to take to fix this" reaction.

I doubt that you would be so lucky as to avoiding the rebar. Without the benefit of those determinations, $3-5k would not be an unreasonable expectation. Engineering is an "exact" science, based upon "assumptions," which the local building dept. may deem you a beneficiary of, or not. It's how it works. Your roof and ceiling structure will determine the cost of a skylite installation. Potentially a substantial reduction in cost.

Are you doing this with a building permit? You'd be smart to involve an engineer and your local building authority. If your municipality doesn't require an engineer's stamp, they may go so far giving you a plan to work from. They may also have info on your soil type. Some things a professional would consider: Soil, frost line, seismic issues, slope, existence of any fill (maybe during the construction of your house the builder filled some areas of the lot), drainage, water table, etc. For general info on building a block wall and a plan showing a footer and rebar placement, see my personal website: http://www.billb.name/diy/retainingWall.asp. At least it'll give you some language for speaking to your building inspector. Bill

I would start by contacting the local utility to arrange an energy audit. That should give you some idea of where your heat is going. A blower door test may turn up some air leaks. Other than that, remember that you don't have a cellar under this room, and you have a big window in it. If there's no room above, you also have heat loss through the roof. You'll lose more through there than through the floor. How's the insulation? I've known many people with similar problems -- room additions that are never as comfortable as the original house. I had such an addition on one of my own houses. The house was on a cellar, but the addition was on a slab, and at a lower level. In addition to the room's losses, all the house's cold air pooled in the addition. I installed a booster fan in the air ducts to that room, but it only helped a little. The traditional answer to this problem is an inelegant one -- supplemental heat for the room. A minisplit heat pump would be a bit pricey to buy, but relatively inexpensive to operate, and would give you extra cooling in the summer as a bonus. Alternatively, a room like that would benefit from hydronic underfloor heat, but I shudder to think what it would cost to install it.