I should know this but I don't:

Does one get more 'bang for the buck' from rebounders when they are in the post positions (4-5?)

Suppose you had two guys identical in every way except that one was a better rebounder. These two guys are going to play the wing positions (SF and PF). Will the team get more rebounds with the better rebounder as PF, or will it work out the same either way?

Yes playing guys at the 3-4-5 will affect their rebounding, there was either a thread on it recently or I just read one from awhile ago after searching and it did say the 4/5 spots did have an effect on rebounding. I'm not sure about the 3 part I guess it would depend on the opponent as if you were going up against a 3rd guard at SF the PF might rebound really well even though the 3 is a worse rebounding position than the 4.

let me get some other threads for you to look at.