Here's my shot:

A call is +EV if it is profitable over the course of a significant sample size. If my ratio to win (let's say, 25%, or 3:1) is greater than the cost ratio to call (let's say call $2 into a $10 pot, giving you 5:1 odds), it is +EV.

A bluffing bet is +EV when your expectation to win the hand is greater with a bluff than with a call. For instance, your opponent is weak tight and you are faily certain he is playing QQ or KK. He checks to you on the Ace flop (of which you caught no part). Your EV to check behind or flat call here is always -EV. The only way this hand becomes +EV is if your opponent folds.

Raising for value is +EV in a couple of areas I can think of. First, when your opponent has a strong hand that you are fairly certain you have beaten. The other time is when you have a strong hand that could easily become vulnerable on later streets. In this case, raising for value should make your opponents call on the draw a mistake, which will be +EV over a significant sample size.

I don't know if I'm right, but there's my shot. I'm not sure what the extra credit elements are.