Q 6 Answer
PASS
This is difficult as you have 16 HCPs and your partner has not bid. You are vulnerable so you should probably PASS.
Q 16 Answer
DOUBLE
You have 10 HCPs and cannot bid 2H over 2C (as you would be promising 5 cards), so you should DBL promising both majors, even though you only have 3 cards in spades.