Thanks to everyone for all of the great advice! This is a great site with a lot of very helpful and knowledgable folks.
In doing things as described above, as far as the roof, if done correctly, as instructed above, what are the odds that it will give us ongoing leak problems from the roof? I remember, as a child, we had an exhaust fan in the bathroom downstairs, and maybe it was just condensation, as previously mentioned, but that thing would squeal in the morning, if it was cold enough outside. Was this due to improper insulation, or from a leak?