use riivolution it supports usbs
No it doesn't

Is your SD card full with brawl hacks? If it isn't, you could always try to split your usb into a wbfs and a FAT32 partition (one for your games, other for your apps, music etc.) If you don't have enough space on your usb I suggest you buy a hdd to store your games and apps. I don't see any other option for usb loading.