How many different formations do you guys use on offense. Do you use a few plays from each personnel grouping or overload on one grouping?

I think it is best to use more than 3 and less than 7 play sets.

I use plays out of all 10 available formations but the 3 empty backfield formations only in hurry-up modus when the opponents pass keying anyway.

Do you need to have offensive and defensive plays selected during training camp? In other words, do you gain play experience for your playbook during training camp?

Yes

I don't use any sets where I don't have the possibility of both running and passing. I also use heavy sets (122, 212, 221, 230) a lot.

I I thought guys just gained skill ratings and positional experience . Is it a larger impact than the regular mid week spin/practices?

As far as I know it is skill ratings, position experience, & play knowledge.

I gonna have to check the rate of growth for play knowledge during the camp spin. It’s pretty small for the mid week spin and actual game