1978 vette many issues

I recently bought a 78 vette and I love this car but there are a few quirks.
I've ordered a Haynes for this car but it won't be here for a while and I have a few days off and would like to start working.

First no matter how much gas is in the car I get a low fuel light I'm guessing its a bad ground or float but I have no idea where to start looking.

My caliper is leaking brake fluid I ordered that a few days ago and it should arrive today so that will be going on today as soon as it comes.

My passenger side window rattles every time someone shuts the door if it is rolled up all the way so I have to leave it down about an inch in fear that it may break one of these days.

There are also a few wires that lead to abrupt stops underneath the hood and I don't think the Haynes will help me figure what they go to.

It drives great and I feel I am getting full power out of it. I just want to fix some of its problems and maybe enter it in a few of the car shows they have out here. Last question whats a good place to order so interior accessories like door panels etc?

Thnx
~drew~

Another issue today the rpm gauge just stopped working. The needle is just sitting in the redline area even when the car is turned off.

But after I noticed that I did get a call from autozone saying my calipers were in. I changed both my front calipers (they were leaking) and decided to change out the brake fluid and new brakes all the way around.

Next I'm going to change my oil pan gasket and oil.
Does anyone have any suggestions on oil? I have a case on Mobil 1 but I'm not sure if that's what I should use in here.