1. Possibly the wheel can be trued but only a shop/wheelbuilder will be able to tell from looking at it.
2. I would consider using just the caliper brakes and if the rear wheel is shot, just replacing the whole rear wheel. this would solve the drum brake issue.
3. Uggh, the stuck seatpost. I get these from time to time and they are a bear. There are a lot of fixes for this but essentially it has probably corroded in place and this is not unlike a weld. It can be super tough and some of the worst ones I have dealt with had to be cut out. First I would put a ton of good penetrating oil through the BB and try to get it to soak into the post/seattube interface. Let that sit for a few days adding a little more once in a while, then try to bust it loose while holding the frame rigid in a vise or similar.
Some try the ol freeze the post with nitrogen or CO2 and the differing expansion rates of the metals sometimes break it free.
Beyond that take it to a frame guy, you don't wanna deal with it.
All the best,
Dave Bohm