First of all, welcome.

Second pair is a tricky proposition. I don't know that you're going to get a lot of firm advice on this. If I were you, I would post several hands where it's perplexing you and get some specific feedback.

So much depends on reads, position, the preflop action, the game situation, strength of kickers... there's so many variables with a marginal strength hand that any firm and hard guidelines are going to lead you astray. That said, someone will sweep by and give you some shortly, I imagine.

Much like most of poker, it depends. I would post as many situations as you can, and with our advice and your experience at the table, you'll get a better feel for it.

In your hand, for example, if you have a read, a fold can be right. I think a raise can be reasonable to see where you're at, and there's an argument for floating him on the flop and then aggressing the turn, if he slows down. You've got a ton of options, but they depend on your read of opp. Personally, I probably float a call here to control the pot size, and raise it on the turn if the card seems safe. Lots of options though.