About the questions with grip and HP/weight modifiers....
It gets tricky here because there are so many ways around being able to regulate anything now it's pretty much impossible to do so. As of right now this comp has no actual start date until everything is evaluated and sorted out to where I, and the people I trust to help me make decisions with the series (Ant, Danger, fcpmarcus, etc.) are comfortable with starting. There is a target date which I believe is in the OP, but everything is subject to change at the moment. I would also hold off on putting any cars up on share at this point in time.
Getting back to the topic, I and many other want Formula D here on GTP and GT5 to remain as legitimate as possible. So the use of any grip multipliers or HP and weight modifiers is strictly prohibited. Like I touched on above, there is really no way to regulate this, so the whole series is basically going to be on an honor system. But again, heed the warnings. If someone is suspected of cheating and it is determined that they are, there will be no exceptions and they will be permanently banned from any future FD comps.