I'm wondering if there was a better way for my friend to play this hand:
Home tournament, 15 min blinds. 3k starting stacks, blinds just went up to 50/100 (next level 100/200). 9/9 players remain.
SB in this hand is jmc

I tend to play a tag-ish Harrington style game, but I've been making adjustments based on how my opponents play.
UTG+2 is sorta weak-tight and MP tends to be fairly loose preflop and a reasonable post-flop player.
UTG+2 limps, MP limps, My friend raises to 300 w/ 99 from CO, button folds.
SB (me) calls, bb folds, UTG+2 and MP calls.
I have about 2500 in my stack, my friend has me covered.
Pot is: 1300
Flop is 2

4

7
SB checks, UTG+2 checks, MP checks, My friend thinks about it and bets 1500 with 9

9
SB moves in for an additional 1k, UTG+2 and MP fold.
1. Did he bet the right amount on the flop or should he have picked a different amount?
2. What range of hands is he ahead of that would give him action on this flop?