Bit Depth

Hi,when im exporting,say for instance,a 1 bar kick loop,to audio,i have been exporting as 32bit.
should i be exporting as 24 or 16 bit? i would be importing the loop then into a project.
and also,if i want to export a project to an udio file to then import for mastering,what bit depth should it be?

Generally speaking you would want to keep the bit depth at the native setting for as long as possible, so if you working with 32fp capable programs then just use that.