SAE 10w30 is a good choice.
should use 5 quarts, put in 4 1/2 and check the dipstick. If it is still a little low put the rest of the fith quart in. Fill the oil filter before you install it on the engine. NEVER install a dry filter. Then pour the rest of the 5 quarts into the engine.
You should drain the oil in the engine. Put engine oil back in the engine because the transmission oil is not made for engines and will hurt the moving parts of the engine if left in.
The 305 was an option on that car, so a 350 should be a bolt-in.
The oil sensor is junk. You MUST replace it. Be sure to put a SMALL amount of sealer on the threads. When you start the engine the oil pump pumps oil up to and in the oil sensor.
If you have the owners manual to the vehicle, it will tell you exactly what to put. Also if you open the hood to the engine compartment, you should find the recommended oil type on the motor where you put oil or it should be stamped somewhere in the engine compartment.
With a 4.6 L engine, should be 4.5 L of oil.
30 weight
to reduce friction between the parts of a car
It depends on what you SHOULD have put in and what you DID put in and the age of the engine. Most of the time it won't make much difference.
it will hold about a half quart of oil
Crankcase oil is engine oil , so yes
5w-20