NL25: hero flops 2pair - line check

[tron]

ist die allererste hand am tisch, also keinerlei infos über villain(s).

a) raised ihr den turn?
b) raised ihr den river und wenn ja, auf wieviel. und wenn ihr raised und villain pusht, callt ihr?

PokerStars No-Limit Hold'em, $0.25 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: ITH Forums)

SB ($40.65)
Hero ($25)
UTG ($22)
MP ($34.80)
CO ($13.15)
Button ($14.20)

Preflop: Hero is BB with :7s, :6d.
UTG calls $0.25, 1 fold, CO calls $0.25, 1 fold, SB completes, Hero checks.

Flop: ($1) :6h, :7d, :kh (4 players)
SB bets $0.5, Hero raises to $1.75, UTG folds, CO calls $1.75, SB calls $1.25.

Turn: ($6.25) :9s (3 players)
SB bets $0.5, Hero raises to $4.75, CO folds, SB calls $4.25.

River: ($15.75) :2s (2 players)
SB bets $0.5, Hero ?