Hi, Autumnbird,
Sorry if you're sick of me responding to all your posts! What day is your surgery? (I'll try to remember to pray for you if that's OK.)
I don't know that there's a big change in risk factors of CSF leak among the different approaches. (The risk may be higher for retro-sig, although I'm not sure). There is definitely NOTHING you can do to prevent it. I think it's pretty rare, and usually results from some small leak from the IAC, or else maybe a small accidental nick to the dura around the brain during surgery. Even if you're unlucky and get this, my understanding is it usually corrects itself one its own. Might mean a couple extra days in the hospital. They will definitely check you for it a couple times before you are discharged.
Good luck!