New Guy, 72 Plymouth Duster, where to start looking?

Hi all, New member in rural Oregon. My father had a 1972 Plymouth Duster he has owned since the late 80's I think. Has the original 318 in it. I recently bought it from him to make sure it stays in the family and I'm wanting to get it back to a daily driver. Not looking to make it a hotrod necessarily mostly I just want it to reliable and safe. For the most part it's pretty original other than a few minor things that my dad has done. Has just under 70k on it now. It starts up and drives just fine. My dad hadn't done anything with the car for a while so when I first go it we changed the fluids, new gas, and battery. It started right up and drove. After an hour or so the temp gauge never went up and the motor seemed to be warmer than I would have thought when I opened the hood. Also the Oil light started coming on but it wasn't consistent. The oil level was full though. No leaks or anything either.
I went ahead and just replaced the thermostat and the temp sending unit, then drove it for about 30 min. The temp gauge did go up but never got over around 150-160 I'm guessing. Also twice it made a very awful sound very briefly. I'd describe it as sounds like metal scraping on the road, coming from the front part of the car. I first looked under the car to see if something was indeed dragging and it wasn't that. Also the oil light was blinking a bit but never staying on consistently.
I'm very new to this but I have a few questions I was hoping get help with.
1) Does the oil light indicate low oil pressure or low oil level?
2) Can the oil pump being going bad? Or are they something that either works fine or fails completely? Could it be going bad and not creating enough oil pressure? Could it also be responsible for the noise I heard?
3) How long should it take to heat up if it's just idling and what temp would be normal?