Buying home with old pool

We are buying an older home with a pool and need to know some important things to ask and who can we trust to service our pool without taking advantage of us. Would greatly appreciate any assistance. The home was built in 1968. Not sure when the pool was built. It has a built in "spa", but the old heater has been disconnected (wires cut, etc.). Owner did buy a new filter and pump. The whole system looks confusing. Not all of the "jets" in the pool work well, but the water is clear. It is made of plaster and looks as if it needs repainting. Help.