JJ in late position Hand Help

[beenben]

$10 rebuy after the break. I'm second in chips at the table with around $36,000, in the cut off with pocket jacks. My pre-flop raises have been respected and I've won all or almost all of my showdowns. Blinds are $600/$1200
and EP has raised to $4200, a standard raise for this table. folded to me and I call; all others fold.

flop is Q 7 2 rainbow;

I check, he bets $4200, which must be about half the pot. I have him covered by about $7,000. I check-raise all in- he thinks and calls with QJ.

I'm debating about whether I should have 1) re-raised pre-flop either to $10,000 or all in? or 2) folded pre-flop or 3) bet the flop to see where I was at or 4) folded to his flop bet. (and I'm wondering why he raised in EP with QJo, and called my check raise when I could have had Q with a better kicker or kings or aces or a set of sevens or deuces).