Generaly , the OL is looked upon as a package. The depth chart gives you opportunity to specify which players you want to play guard and which tackle.
Someone here once figured out the optimum setup for the OL . But I dont know it.
An easy answer is to just put your best lineman in the order you want em in in all the columns and the AI will sub accordingly.
In out settings are for what percentage you want you player to run inside(up the middle) or outside(end run).on a run play.
Seems to me lb on the line would be in one of two situations. When trying to stop run play. Or when looking to put more pressure on qb.

Gotcha and Dbs is it still like on the old site? First 2 dbs are corners and 3rd and 4th safeties and 5th nickel which of course gets disrupted as u sub?

If you are in D2 or above You can specify which player is corners and which safetys in depth chart . Haven't been in d3 for so long not sure what is there ?

DIII you can't break the sub-positions down. You can cheat a little bit on that, because although you can't specify OG/OT, OLB/ILB, etc., the engine still uses the same math. If you put a guy with fullback stats as your #2 RB, he'll act like a fullback in the engine. Problem is when your #1 RB gets tired and your FB is now playing Speed/ Possession RB. One of the many reasons I moved up...

Thanks planning on moving up after a season or two been away for 3 years and just getting up to speed again.