RE: broadhead flight?
See, I disagree somewhat. I think it's more of an aerodynamics issue, not just a tuning problem. Pften times though, most shooters use tuning adjustments to correct the problem.
I say this because I myself am quite adept at tuning my bow. But I also have taken it to our local bow shop expert. Cost maybe 5-6 bucks.
The aerodynamic differences between field points and broadheads (especially long bladed ones like the Thunderheads) is substantial! This was one of the reasons mechanicals became so popular so fast. "They shoot just like your fieldpoints!"
My broadheads (NAP Crossfires - 100 gr) shoot 3-4" right @ 20 yards. So I move my rest. In fact, I have taken a fine blade and scored the rest to mark where fieldpoints shoot, and broadheads. Gets me very close, and I fine tune from there.
I do believe you need to start with a well tuned bow (pro shop tuned), otherwise you could be chasing your tail.