rust round the towing eye isn't a prob, thats just the rear valance, nothing structural. Just clean it up & spray, doen't have to be an amazing job as its not something you'll see.
I wouldn't worry about the water temp gauge not working either, probably an easy fix. 1st think pop the bonnet and check the plug to the black temp sensor, will have a brown & red/yellow wire. Should be located in the plastic flange at the front of the block, where the radiator top hose goes to.
What you need to check is that the bottom hose is stone cold till the oil temp is arround 80 degrees, if it gets lukewarm straight away then it means the thermostat is stuck open/missing so might explain why the gauge isn't working.
