How hot do you need to get the bait head for the paint to stay on the head? Can I just use a lighter, an oven or something like that, or do I have to do it a different way.

Not sure of the exact temp, but you can use any of the methods you mentioned for powder painting.  I use either a torch or heat gun, then bake in oven for 20 min

Are you just painting a jighead? If I'm painting like an 1/8 oz shakeyhead I just wave it back and forth over a lighter for about 10 seconds and swish it through the powder. Make sure the power is fluffed up really well. I stir mine about every half dozen jigheads with a toothpick to keep it fluffed up so you get good coverage without clumping on the head. You can bake them after that to make it last longer but make sure you clear the eye out first  . I usually don't bother with baking my shakeyheads because the rocks usually eat them before the paint has a chance to wear off >.