RE: Confused about Resizing and Head Space
In answer to your latest question, Yes the belt will go into the die but if the die is cut properly and you adjust the die as Bigcountry said you will have no problems. As for closing the bolt, if the cartridge was originally fired in that rifle you should have no problems closing the bolt, UNLESS the case neck is too long. You should always trim your cases after sizing to the 'trim to length' specified in the reloading manual. Even if the cutter just touches the case mouth. Trimming squares up the case mouth to the bore which attributes to better accuracy.
Also, if you try to chamber partially sized cases into another rifle of the same chambering you may end up going to the local gunsmith to have it removed because chambers in different rifles can vary.
IMHO, I suggest FL sizing.