To answer some of your questions:
1) that grinding noise is your throwout bearing, in order for it to be replaced the tranny has to be removed. If you do not replace it, it may disintegrate at some point and take out your clutch with it.
2) your sending unit in your gas tank is shot. Needs to be pulled and changed.
3) looks like your tires are ground hawgs, and probably a bias ply, hence the reason they wont balance properly. Either get new tires, or try balancing them (bead balancing may help those)
4) it wont hurt to change the fuel filter and do other maintenance, but you probably arent going to get any more power out of that little 4-banger. Its a 2.3 L engine, you wont go much faster than 50. If you regeared the axles, it would help out, but if youre going to go through that trouble, than youre better off just swapping out for better axles. The 7.5 and Dana 28 in your truck are notoriously weak, although with that anemic engine, you probably wont have much breakage.