You are entitled to12 weeks per year of unpaid FMLA time. You can can opt to use your unused sick, personal and vacation days to get paid. If you choose to do that then you will not get paid for vacation once it comes around or sick days if you take any. Go to HR and as where you get the forms and if they don't have them they should bbe able to to tell you where to go. sometimes a good OMS has them as well. Also you are not committed to taking the amout of time you requested off. You can always go back early. I had requested 6 weeks off when we had our baby and went back to work after 4. also with FMLA you don't hve to take all 12 weeks in one shot. It is possible to break it up thru the year. So you can take like 2 weeks ater teh birth and then maybe take a few more when your wife opts to go back to work to save on daycare.
trust me when I tell you this. You don't need alot of time off with a newborn. I did it so my wife didn't have to get up everynight at first in the middle of hte night. If your wife plans to breastfeed than this isn't an issue and you get to sleep thru the night. But be warned, you will get bored since all a newborn does is eat sleep and poop.