Convert a 60 fps video to a 24 (film) video - is it possible?
You can, there's a lot of frame blending algorithms that will do it for you. That said, none of them is really great. All your 60fps footage will have a different look than your 24fps footage. You flat out cannot evenly go from 60fps to 24fps, there's just too little overlap in where the frames actually show up on a timeline. For frame conversions of that magnitude (24p->60i for TV, for example), the big boys have traditionally used telecine/telesync setups where they would literally film an image projected from a movie reel with a television camera.  

Consider shooting 50fps (if that's an option). It's much easier to go from 50 to 24 (drop every other frame, then drop one frame a second) than it is to do 60->24.