I have to say a couple of things. First of all, don't use WBFS. You'll regret it later for how inconvenient it is. It is a very outdated and obsolete file system. 'Back then', WBFS was the only way to go, but with the advancements in wii hacking, it is no longer necessary - thanks to the ability to use FAT32/NTFS now.
Just stick to FAT32 or NTFS. And if you do decide to use FAT32/NTFS, in my opinion there is no reason to split a HD into multiple partitions. 1 FAT32/NTFS partition is good enough and you can store anything else you want to on it, not just limited to Wii game backups.
SD card is required for the hacking of your Wii. You'll see why once you read the guide (I assume you will follow the softmod any wii guide here).