Jenn - use your own librarian skills first to do lots of internet research, which should be a cake-walk to you! Try to find a women's group in your area that does this work by helping each other, trading skills. They will have experience in remodelling their own old homes and probably won't give you the frustrations that contractors come with - such as changing dates on you, doing several homes at the same time and pulling crews from one to the other, etc. I work with them, so I know why they need to do this, but as a homeowner I find it irksome. A women's group may simply do it for a price, rather than an exchange, when they know how much volunteer work you do.

When you need to use contractors, ask for estimates (I'm sure you already know this). You should get four for each job you are considering. The range is shocking but don't worry about trying to go for the highest, it's not always the best. I was given a price twice that of the person I eventually chose to do my roof and the first guy didn't even go over the extra ventilation needs that should be put in place. I didn't go with the cheapest either. I work for the state and we have to do that, with some awful results sometimes. Go with someone you feel trust in, that looks you in the eye and goes over the details, answering questions. Call their references. They should be able to come out to your home in the late afternoon, early evening or weekends.

You probably need new plumbing. A friend with an old house in Seattle put in a new water heater that made no difference at all, but when she had new plumbing put in she had gushing faucets for the first time in ten years. Your costs on the east coast are cheaper than on the west coast, so I can't give you any price ideas. She used someone who "did jobs" rather than plumber and had to keep calling him back to fix leaks, so not a good option. Her determination to save money caused her to have to deal with later water damage.

What Lori said about re-framing the windows is spot-on.

I agree with everyone else about the fireplace. The gas one has to be removed professionally and the whole fireplace and chimney inspected, and possibly modified if it was always a gas fireplace.

What's wrong with the floor boards in the second and third floor? Can't they just be sanded and sealed - you don't want to do that yourself either, I don't think.

Why are you worried about plaster walls? I have sheet-rock walls and hate them. My friend with the old house has plaster walls and I really envy her - and she has the same kind of wonderful wood floors that you have. Sigh!