Great Question. Joe has given you a lot of good info from my perspective. My husband & I have renovated numerous older properties, including the 1860-1880 one we are in now, and a 1790s stone and log structure They do pose some unique problems, but by and large they are well built (they are the ones that have lasted!). One other resource that you might check is your local historical society or the office that handles historic registries in your area. They have some good info tha twill be especially helpful if you intend to register the home. You may, however find that the restrictions that such a registration carries with it, outweighs the benefits to you personally.
Best wishes as you take on this project. It can be very rewarding!