trying to figure out when you put a linebacker on the line does this mean he becomes a down lineman, changing your front from a 3-4 to a 5-2 if you move 2 LB's to the line?
Also if you have 2 LB's blitzing 30% of the time does that mean they both blitz at the same time?
Can someone please explain what the position roles tab means?

1. LB set to line. That is probably the right way to think about it. They will not drop into coverage, and their ratings will be grouped in with the DLs (as I understand things).
2. LB Blitzing. NO. If your formation has any number of LBs blitzing...when the playbook calls for a blitz....it will pull ONE of those LBs. Over time the total % of blitzes will approximate the PLAYBOOK setting and the individual position that is blitzing will approximate the FORMATION setting.
3. Position Roles tab: This is where you can set your own "attribute levels". You can use defaults, you can use the GUESS formulas, or you can come up with something on your own. This helps in the depth chart settings to identify which players best fit your specific positions (ILB vs OLB, S vs CB, DE vs DT, etc, etc)