Hey not sure how crazy big your gonna be going,but in the mx world... broken collar bones come from the helmet smashing your collar bone. You can get inexspensive neck rolls,EVS,661 and others have them. The LeAtt (sp?) braces are the new thing to prevent hyper extension of the neck which is where you get into serious trouble,but they are pricey 300ish.
I where shin pads,and of course ankle braces(my ankles are shot). Some days I have to roll out with a wrist guard or two(my wrists are gone too).
Mad props to you for steeping the game up,be safe and FILM THAT CHIT!!!