I have an automatic transmission, and it is just fine, I don't think you should have many troubles with the transmission. And yes, you pretty much got it on the cooling system. I haven't done much research into the heater problem, so I can't tell you much as far as that is concerned. Good luck with that man, I think 5k would be a fairly decent offer as long as the seller is reasonable.
Edit: I don't think that the power steering reservoir being wet is a major issue. The cap on the reservoir is designed to allow overflow if too much fluid is added (at least that is what I have been told). Mine had fluid on the outside of it when I got the car and it hasn't given me any issues in the 2500 miles I have driven it. Fingers crossed on that one, but I think it is okay.