Some questions about 2000 Silverado

I've just replaced my 92 C1500 (lost 3rd & 4th gears) with a 2000 Silverado and just wanted to check on a few things.

1) there's a relay in the fuse panel where it says "put a relay if you have power locks and remote", and the locks cycle when I go through the keyfob programming sequence. Presumably this means I have the remote opening option and all I need is a keyfob?

2) the power-adjustable mirrors rotate up and to the left, but not down or to the right. Is likely to be the switch, a fuse, or something fundamental in the wiring? I don't want to just start pulling off door panels without some idea of where to start.

3) I have three different sizes of tires... Front: 255/70/R16; back: 265/75/R16; Spare: 245/75/R16. Are these all likely to be on the same rims, and is there any good reason to stay with different sizes? I need to replace both front tires, so I have the option of making them match the rear.

1. i know nothing about the remote door lock thing.

2. it sounds like the switch on the mirror is shot. its about 45 bucks. i had one replaced around a month ago. it cost me 140 for a mechanic to do it.

3.assuming you have a 2 wheel drive truck, i see nothing wrong with the front tires being a bit different than the rear,but it certainly makes sense to make em all the same size. just dont mix sizes on the front or the rear axle. if it is a 4 wheel drive,all tires must be the same size.

:)