Those are struct names though. So they wouldn't be in there. They did share some headers with the MTA developers though and that's where we got bRenderScorched from. i think the body part name is ours though.
Definitely. Early GTA Online was heavily inspired by MTA game modes.
For example, the races on crazy roads floating in the sky was a hallmark of MTA. It's far too abstract to think R* came up with that idea independently of the many years of prior art in MTA.
It's a shame they only copied the game modes and not the architecture, as GTA Online's biggest downfall is the P2P networking.