Re: Paint Job
Best results, probably the paint gun. On the other hand you can get very nice results with a spray can providing you use quality paint and as pointed out above, take your time with good technique. I've done both and prefer a spray can since it is a small job compared to painting a car. I like Van Sickles Tractor Paint as it is durable, covers well and looks good.
No matter what you are going to foul up the paint job during assembly and later on through regular use so a great paint job is something that doesn't last forever and will require touching up later on. That's one of the main reasons I like spray cans, the ease in touching up.
Good luck and have fun.
Someday when I grow up I will probably lose interest in toys with wheels, but until then...