The heating problem is most likely your thermostat.
The fan(s) in front of the radiator will not come on until 105-110 or with high a/c pressure.
Do you have a 2.3 0r 2.6?
If you have a 2.3 the main fan locks at 100-105c. It spins freely until then.
If you have a 2.6 its a viscous fan which spins faster the hotter it is. Wait till the car gets hot, turn the car off and try spinning the fan, it should have some resistance.

The oil pressure is a little worrying. I would change the sending unit.