unneeded desperation

[joao_,martins]

I am playing a live MTT at a local casino.
Blinds 600/1200. 25 people left, final 10 gets paid.
I've got 18k, good enough for second in chips at my table, with the chipleader at around 22k.
UTG has played tight all day and has recently gone on an aggression streak ( he has raised the past 3 hands all-in and won uncontested ).
UTG limps this hand with around 7200 total.
MP limps with 8900.
MP+1 limps with around 10k.
I am CO with J [img]/images/graemlins/heart.gif[/img]- 9 [img]/images/graemlins/heart.gif[/img] and I limp.
SB completes with around 12k.
BB checks with about 4k.
FLOP:
Q [img]/images/graemlins/spade.gif[/img]- J [img]/images/graemlins/diamond.gif[/img]- 9 [img]/images/graemlins/diamond.gif[/img]
UTG bets 2k.
MP raises to 7700 all-in.
MP+1 folds.
And I decide to fold... deciding that I was either dominated or either player had quite a few outs to outdraw me and take a big chunk of my chips.
*Would this be the correct move most of the times?
Anyhow, UTG called and he flipped over K-Q and MP flips over A-Q ( which I never would have put her on ). The turn was another nine and i would have practically sealed the deal as there would be only one queen left to beat mny hand. Needless to say the river was not a queen and I would have taken in 19700 more chips.

Next hand, I felt some sort of desperation over me making that fold... and I decide to try to blind steal with Q [img]/images/graemlins/diamond.gif[/img]- 5 [img]/images/graemlins/club.gif[/img].
I open-raise to 4k.
CO who has 22k calls me ( which was the last thing i wanted ). CO was playing pretty tight pre-flop, but would call outlandish sized bets on mediocre draws and often hit... that is how he built his stack.
Everyone else folds.

FLOP:
Q [img]/images/graemlins/club.gif[/img]- 4 [img]/images/graemlins/club.gif[/img]- 2 [img]/images/graemlins/club.gif[/img]

What do you bet here, if you bet at all? And if you dont go all-in and he raises you must you call due to pot size and how many chips I put in?