'01 Altima Problems

[Gustav832]

I have a few minor problems with my car and I'm not quite sure what to do

My gas gauge doesn't really work, half the time I fill the tank, it will never read above 1/2 a tank then others it reads full, and then sometimes I"ll start the car, read 1/2 a tank then 20 min later be on empty. Any ideas?

Second, I purchased a new remote through a dealership and I've tried programming it 100 times, didn't work, then the dealer tried it, didn't work, and they're asking $80 just too look into what the problem is. Before I do that, was wondering if anyone had any idea what is going on.

On a side note, one of my license plate lights are out, whats the best (or only) way to access that to change it?

On a side side note, this is the first Standard that i've owned, and i know that with automatic transmissions, you can do a transmission flush, is there anything equivalent with a manual? Also i've heard that with automatics doing a transmission flush can be damaging if the car has high mileage, is this true with standards? (100k miles on mine)

one more thing- I have to buy a new relay for my blinkers, and there were two kinds a Loud Switch and a Electric Switch, and the Electric was $1 more. Whats the difference?

Thanks alot!