The cossie should be quite cheap to run unless there are the usual problems to solve....if it doesn't run 100% right then you could need to replace fuel pump, pump loom, coil, map sensor, whole engine loom etc as nothing worse than a popping and banging cossie.

If the engine has been looked after then unlikely to go bang but if the budget is tight I would at the very least get a good compression test and try it with a cold engine on a damp day.

The 4x4s can break boxes and diffs.

Old cars are pretty horrid to use daily, I have a 205 gti but only use it a few times a week and take something new on other times. I would get rid of it in a day if it was my only car.