home game 6 hands
sb/bb 5/10 (usd 1/2)
BB 1145
CO 3200
BTN（hero）3045

CO open 40，hero BTN with Kd5d call，BB call，pot 125；
flop Qd4dTs
BB check，CO cbet 250，hero call，BB call，pot 875；
turn Ks
BB check，CO cbet 500，hero call，BB allin 855，CO call，hero allin 2755，CO call，pot 3440，side pot 3800；
river 2h
BB AdJc won the pot
CO KcQh won the side pot

BB is an ABC player can play good hand and make nice fold sometimes play a little bit too much marginal hands. CO is a loose and passive player cannot fold nice hole cards no matter what board cards are most of the time, like a calling station.
I do believe my decision on turn was wrong. The best action was flat call to see the river. CO could have a hand like AQ or QJ and probably would never fold so I went allin on the turn.
Questions:
1, what is the best way playing this hands?
2, how to calculate the pot odds on three way pot? Would (2755-855)/7240=26.2% be right?
3, what is my winning rate on the turn? Suppose BB hitted the straight on the river, should I consider 3 persons' win rate or just make it 2?

Thank you very much in advance.