Tiger Shark:
Blades/Claws/Fangs
When this character is given a close combat action, you may roll a d6 after making a successful attack roll. The result replaces this character's damage value, then that damage value is locked.

My question is can Tiger shark use B/C/F with Blood in the water?

Yes, it is no different then how Charge gives a close combat action as a free action.

Yes. If it granted a close combat attack instead of a close combat action then you wouldn't haven been able too, as BCF requires a close combat action to activate.

Followup question:
If tiger shark uses charge, does the move action that is part of charge qualify for the free close combat action after the charge has resolved?

Charge has Movement, it does not have a Move Action. There is a big difference when you look at how powers interact together.

Charge itself is a power action. What his ability allows is a move action using his full movement and then giving a close combat action as a free action.