Considering 97 GS

A relative has a 97 GS with 96K miles. There are some issues:

1. When it rains, passenger side floor gets wet and trunk lid leaks.

2. Check engine light is on. "Goes out for a few days if you change the O2 sensor." Haven't scanned for codes yet.

3. Coolant level light on even when bottle is full. Car has overheated but not since sensor replacement. (light next to check engine)

4. Needs battery, timing belt and radio upgrade.

5. headlight lenses are fogged and yellow.

Seems to run good, but I am concerned with the warning lights. Any comments would be appreciated. Thanks

I bought it. P0171 and P0174 - Lean bank 1 and 2 Is this O2 sensors?

Thanks