re: Poker & Flash Draw after flop , worth going all in??
With the flush draw & 2 overcards in the first scenario you're ahead (marginally), so it's entirely situational as to whether you call this guy.
Generally at this stage of a tournament I wouldn't bother. If it was a cash game I'd call every time. This sort of scenario is where the whole difference between cash games and tournaments comes into affect. I don't know what the payout schedule was for this tournament, but in a cash game this call would be +EV, whereas at this stage of the tournament it's likely it was a -EV call.
If the person pushing in front of you is a really good player then you might want to take a little gamble to try to knock him out right there. If he's a complete donkey, like the guy you've described, then IMO you're better off waiting for a spot where you're a huge favourite, or folding and continuing to chip away at his stack in later pots.