Re: Beater striking position
I personally don't place my beater based on where it is regarding the center of the drum. Meaning top of center, center or below. I usually adjust the beater height based on the feel I'm after. Sometimes it's on center, sometimes not it just depends on whether I want a lighter feel and/or quicker action. Also tbh it only takes very very small adjustments to get a different feel so I doub't I'm that far off of center anyway.
As for the physics side of it, well I suppose because you're striking less of the drum head, you won't get as much of the attack of the head as you're moving less of the head to get a sound out of it. If that makes sense. I would say it depends on the size of the bass drum as well. Honestly unless you have an extremely tall beater and a bass drum 18" or smaller, I don't think a couple inches of height will make too much of a difference.
Although with all that said, I find the idea of placing your beater off center for more tone and less attack a bit odd. There are better ways to get more tone vs attack of the head like going with one ply and getting a felt beater. Not an Iron Cobra felt beater, a 100% felt beater.