Noob Fixing a 1993 sierra gt, 5.7 engine, 2wd, positive differential

[Drjeseuss]

I recently acquired a sierra and it is my first time ever owning something older than 2005. i was hoping to get some info On DYI repairs i can do to the truck and some tips on maintaining a vehicle like this. The engine is in really good condition what i need help with is more appearance and a few tech questions. will take all the help i can get.
*First off the gauges arent reading accurately, the fuel is about a quarter tank off and oil/heat doesnt seem to register at all.
*paint on the rims looks scraped off, they are aluminum. was hoping to fix that on my own if possible.
*some of the plastic buttons are chipped or missing,like ac up or down and things around that. can i replace them or do i have to buy the whole piece new.
- yes i know i can youtube a lot of this but its hard for me to find things specific to my car and dont wan to do anything im not suppose to