99 in CO facing button 3bet

[mxrider]

Villain is a descent player overall 20/17/3 with an overall 3bet of 7.6 and a button 3bet of 11.

Question 1: How big of a pair should we be calling with vs 4 betting vs folding??? I feel like folding here is just too nitty overall, but I may be wrong.

Question 2: once we do call and hit our set, what are your thoughts of my c/r???

Full Tilt No-Limit Hold'em, $2.00 BB (5 handed) - Full-Tilt Converter Tool from FlopTurnRiver.com

SB ($128.75)
BB ($195.50)
UTG ($232.15)
Hero (MP) ($362.65)
Button ($210.35)

Preflop: Hero is MP with 9, 9
1 fold, Hero bets $6, Button raises to $19, 2 folds, Hero calls $13

Flop: ($41) 5, 9, 8 (2 players)
Hero checks, Button bets $25, Hero raises to $66

[TheDeKay]

1. I prefer to 4bet-call here. He seems aggro enough and calling gives A, hands like KTo good equity and B, him the opportunity to make our life hell on Axx, Kxx, Qxx etc.

2. c/r is fine, since he might shove with draws and overpairs. c/r more!

[given1982]

Without any 4betting history, I just flat 99 and TT in this spot. C/r is good--hopefully you're balancing it with bluffs on this board.