Heads up class clarification

[JP1738]

Couple of things here given this is semi-related and I don't want to start yet another thread elsewhere:

If I were to run someone in the same class as me, but one is an auto and the other is a stick, is it still heads up? I don't think they run class with each other, but I didn't know how it applied during the race.

Also, where are the procedures for the actual race itself defined? As in, where does it say it's a handicapped start bracket race, must dial at least your index, heads up run if you match up with someone in your same class? I just looked through the rulebook on Stock and it really doesn't describe the actual running of the race with any detail. I understand how the class is run at this point, but I'd love to find an official NHRA resource that describes it more officially that I can point others to who have questions about the class.