3. South is too strong to Pass, but not strong enough to jump to game. If responder's values are in spades (KQx  xxx  Qxx  Jxxx), game is no good. But, if responder fits a minor(s), and has a decent hand, game is good (Jxx  xxx  AJxxx  Qx). I think 3 is the best call because it allows responder to "punt back" with 3 if not sure. A game try in the suit 1-under leaves the least wiggle room. Note: Vulnerable at IMP scoring, opener should be more aggressive than at other vulnerabilities or forms of scoring.

3. Game is unlikely (especially after West's takeout double). That rules out 4 or a game try. Pass makes it too easy on West. Surely, your opponents can make something, and you want to make it harder on them. Your side has 9 trumps and you should compete to the 3-level with a non-invitational 3.

Double. Warning -- this assumes the partnership uses Game-Try ("Maximal") Doubles. If there is any doubt that your partner might forget, then don't risk this call (unless you enjoy being minus 530). Assuming the partnership can be counted on to properly use this convention, South's hand should employ it. He is too strong for only 3, but not strong enough to jump to game on his own.

2NT. This is a natural game try. Partner can pass, bid 3, raise to 3NT or bid 4. He will expect about 18-19 balanced (with less, you would have opened 1NT and with more, 2NT).

3. Yes, the opponents have been quiet so far, which is a little strange, but do you trust them to remain silent if you settle in 2? Bidding 3 isn't invitational, and you hope it will buy the contract.