YIkes, okay, I'll dive in when I can (in LA working). I'm never sure when I'm walking on copyright, so I'll trust you to keep me honest...
Does the grabber take the same sort of penalties as the grabee? What can they do? (I'm specifically imagining here the old "villian grabs an innocent bystander, holds a gun to the head" scene)
I'd almost want a true Grappler to be able to take a bonus on "grappling" someone who has him in a Grab....(that "innocent bystander" is actually Jet Li, whoops)
You know what, I can't really tell from the rules -- again, they focused on streamlining them -- but I'd say, personally, that of you can "attack with a light weapon", you certainly as heck can "threaten" with one.
For the second one, again, not covered in the rules. I'd assign a flat bonus, personally, or sklp the initial unarmed attack, to turn the tables. No need to "grab" you opponent, when he's nicely enough laready moved into your square.
Let's move on ...
Prereqs to Trip and Throw? BAB +1 for Trip, BAB +1 and Trip for Throw.
Initimidate is under Perusasion.
Diplomacy is under Persuasion and works generally the same, with adjusted modifiers for the scale of the game. Rules are written more clearly though,. Everything's written more clearly ...
For autofire, you do actually need Burst Fire feat to unload full auto on a single target. Also, such an attack is not an area attack, so Evasion doesn't work.
You can also brace before area autofiring, to reduce the penalty to -2. Not a ton you can do there. It's actually AIMING that gets the honey, with Careful Shot, Deadeye, and some Gunslinger talents.