Playing on an app, so table dynamics are splashy. Two questions, do you bet flop? Also what sizing is best on the turn 1\3, 1\2, 2\3, 3\4?

Hero co($100) Qd8d $3
Sb ($200) calls
Bb ($75) calls
Flop ($9) Kc8s4c
Check x2
Hero $4.50
Both call
Turn ($18.75) 8h
Check x2
Hero bets $6.50

One end I wanna play for their stacks, but think my range benefits from block betting. If heads up to the turn do you use bigger or smaller sizing? 3 way is bigger or smaller sizing preferred? I wonder if you split it by kicker. Q or ace kicker can use larger sizing and 87s 98s hands smaller sizing? Not sure what other hands use larger sizing? Kk? 44? Combo draw 7c6c?