22+, At, A6, A5, Kt : C-bet this flop to build pot
Ax, KJ, QJ: C-bet this flop probably 60% - 70% of the time

Ok, that was my answer from part #1, #2 above.

Let's see... now on to part# 3.
1. Are you vulnerable to a flop pot-sized raise against your flop c-betting range from Exercise 2 if Villain has KQ? Since I know he has KQ (your parameters to the question) I am only vulnerable if I hold QJ in my range so far. Even that hand has outs, but is currently beaten. Thus, if I KNOW he has KQ, no, I'm not very vulnerable. I don't know that this is what you were asking for though, as there isn't a lot of math present here. My impression is you want to know how many hands out of my range are already beat, vs. my odds of improving to be able to catch the lead in the hand...

2. Are you vulnerable to Villain calling the flop with KQ and betting 2/3 pot whenever you check the turn? Let's see, since I know villian has KQ and is c-betting with a non-made hand at this point, the same holds true for both question 1 and 2. No, not vulnerable unless I hold QJ.

3. What is your flop c-betting range trying to exploit in Villain's play? Well, the obvious answer is my c-betting range is trying to build value in pots where I'm currently ahead and also entice villian into continuing in the hand with a poor holding. Also, my c-bet if I'm holding air is to represent strength and force out a better hand... all standard C-bet answers which I don't think is what you are looking for here.

So I'm going to go back, re-read the questions again, see if I can figure out what math part we're talking about and how to apply it, and then hopefully, work hours permitting (lunch is over) figure it out... or figure it out tonight when I get home... either way, I'll check back in as soon as possible.