BTN opens 2,5x and BB calls.

Flop is 985tt (5,5bb)
BB Checks
BTN bets 4

1) First how much should Hero defend?

1-A is 58%, BBs range is doing a little better than BTNs on this board, the dynamic board favours the player in position, so is it reasonable to say that BB should defend 60%?

2) We wanna develop a CR-range for BB

BB got 12 comboes of 76o and 3 comboes of 55 to valuecheckraise. How many bluffs can I aprox add?

I went with 30 bluffs which were:
Qd4d
Jd4d
Jd3d
Jd2d
7d4d
6d3d
Ad4x
Ad3x
QdTx
QxTd
As7s
Ks7s
Ks6s
Ks5s
Qs7s
Qs6s
Qs5s
Js6s
Js5s
Ts6s
7s4s
6s3s

Do I got too many bd fl draws? Which hands would you rather use as bluffs? Do I need some more flush draws

The BB checkraiserange: