Some answers for your 940 questions:

1. The best answer here is to get some used door panels---they should be pretty cheap at a junkyard, and they are not difficult to install. See the FAQ for details on the procedure.

2. If you can live with the seats the way they are, apply Lexol to preserve them. If one or more sections are too far gone, the bottom cushions of the fronts, and both parts of the back seat are very easy to change. If the front backrests are bad, the simplest thing to do is replace the entire seat. (not too difficult either)

3. Loss of coolant is most likely something minor, such as a hose connection or one of the water pump seals. For some reason, the thermostat housings on these cars seem to be prone to corroding (not hard to change, as long as a bolt doesn't break off) Could be the radiator too---if yours is original, it is well past its average life expectancy. Even if it's a head gasket problem, that's not horribly difficult on a Red block. Worst case scenario is a problem with the heater core. For that, the entire dash has to come apart. Bottom line: track down the leak, fix it, keep driving it. As long as it runs well and isn't using lots of oil, you should be OK for quite a while.

4. Carpets and interior trim parts are best obtained from a junkyard, same as with the door panels. Depending on what color you are looking for, and where you are located, I might be able to help you with some items, or point you to someone who has what you need.