Camping Kinzua

There are several boat access primitive campgrounds.  None of them, though to my knowledge are free.  If you want to camp near the lake there are acres and acres of possibilities but the forest service has a "dispersed camping policy"
 
you must be 1500 feet away from the lake and away most major roads and tourist sights;
http://www.fs.usda.gov/activity/allegheny/recreation/camping-cabins/?recid=6083&actid=34
 
as for the major boat-in campgrounds.  the only two I know are along the main stem; hopewell and handsome lake.  a more thorough list is here:
http://www.fs.usda.gov/activity/allegheny/recreation/camping-cabins/?recid=6083&actid=29

Both hopewell and handsome lake are primitive campgrounds... and as such, there's not much there.  I think both places have potable water and the "vault style" bathrooms.  you don't get much for $12/night.