Your opponent's fold to cbet can give you an idea of how he behaves in general when responding to cbets. You're right to note that it's an average, and it can't be applied literally to every single flop in every single situation. Also note that something like a 10/5 is going to fold to cbet less than something like a 20/15 on average because they will have better hands to see the flop with, so you have to take their fold to cbet in context with their pre-flop ranges.

In general, a tagg with a fold to c-bet of more than 75% means that they're usually just going to be continuing with good pairs and draws, and they're so tight that you can just pick them apart with bluffs. Something in the range of 55%-65% usually means they are going to be either raising you on a bluff sometimes or floating sometimes, but not enough to make your life too difficult. Around 45-50% means they are doing it enough to put you to difficult decisions (ie: they are playing fairly balanced), and less than about 40-45% means that they are probably trying to be too fancy on the flop so they end up spewing

Fold equity just means the value you get from having your opponent fold, and pot equity is the value you get from your hand's showdown strength. Long story short, the more outs you have against his likely range, the better your pot equity. I'm not sure about that equation you listed there, but it looks like it would have something to do with an all-in semi-bluff.

Once you get a feel for this stuff, you can start to look at how your c-betting range looks on these flops to see if you're exploitable with bluff raises on the flop. It's not so much that you care if you're exploitable against opponents who will not adjust, but it will help to prepare you to deal with players who play in different ways (ie: raising flop c-bets a lot).