You won't be able to format it using windows. You'll need to use Linux or OS X. Other than that, I'm not seeing anything that states max size of a FAT32 volume... except for in windows... So don't use windows to format it or you won't get the full size.
According to http://en.wikipedia.org/wiki/Fat32 maximum size of the FAT32 partition is 8TiB, but you cant format it on windows (use linux) and you are going to use quite large block sizes. My experience is that windows has issues even with 400GB HDD formated fat32.