If you go to your local library, check out a copy of the Haynes Body Repair and Painting Guide. You'll find that most of the book is devoted to preparing the surface to be painted, cleaning, and sanding.
The executive summery is: Clean, clean, clean. Sand with progressively finer grit paper, until you get to about 600 grit, clean, clean, clean. Paint, several light coats are always better than heavy coats.
You can get a ver professional looking result using spray bombs on small projects like a dash, it all depends on following the directions, and putting the paint on light. You can always wet sand any flaws out once the paint has cured, and put another coat on.
I'd be tempted to just get the truck running first, with the stove bolt in it, then tackle the interior and exterior.
Do you have a shop manual for the truck?