gauge drops to empty and low fuel message comes on

Dealer says need a new transmission. Say cannot really repair satisfactorily. Is this correct?

the headlights do not come on at this time until I actually turn the switch to the headlights

When in 1st gear but goes on find in three and drive on hiway

I changed the belt prior to the harmonic balancer & 4 times after the balancer-even tried a Gator back belt, changed the tensioner also. I isolated it to the main belt. Took it to Chevy mechanic claimed dirty pulleys-cleaned them all, they put on a new belt-one month later same morning chirps until warm up...Help what gives? Thank you.

Had oil sensor replaced now I have a noise under hood

My oil pressure gauge is pegged at 80 psi - the sender needs to be replaced, is this something I can do?