1/ Can I use some variations from the Beyond 531 book (like FSL, Joker) for the N.O.V template or do I need to stick to a standard 531 ?
Stick to the standard 531 - if you do the NOV template correctly, you don't need the other stuff. Too many people take the easy way out. Makes me laugh.
2/ Can I cycle N.O.V and S.S.S templates only (I love them) or more variations are needed like FSL, Joker etc...?
Probably need some variation.
3\ Do you guys always include some conditioning (sprints, box jumps...) regardless of the template ?
Box Jumps are NOT conditioning. Other than shit programs (xfit and I'm guessing PX90), no one other than those with webbed appendages do jumps for conditioning. Let's clear that up. And yes, we always do some sort of conditioning. It takes NO TALENT to be in shape. None. Too many people with low expectations and work ethics.