You can't go wrong with either the Wasabi V3 or Wiikey 2. I have a Wasabi V3 in my Wii (soldered, no clip) and it works perfectly with no problems at all. I have a D2C2 drive. Everyone around here who has experience with the Wiikey 2 says it's a great chip too. I only bought the Wasabi V3 because the Wasabi chips have been around longer than the Wiikey 2 and it's been tried and tested to be rock solid, so I went with experience. The Wiikey 2 is $10 (USD) cheaper than the Wasabi V3, so maybe that will be the deciding factor for you. Also, if you have never installed a mod chip before, do yourself a favor and order a clip with the chip. I am an experienced mod chip installer so soldering in my own chip was no problem for me, but I don't recommend soldering your own Wii chip if you've never soldered anything before, especially on the D2C/D2C2 drives because there are some very small solder points which cannot be accidentally bridged.
The homebrew channel acts as a front end for installing WAD files and other homebrew apps to your Wii quickly and easily via SD card. You will need it if you ever want to install your own downloaded WiiWare or Virtual Console (VC) games, or use ftpii, or use any other homebrew apps on your Wii.
FYI, if you haven't updated your Wii console to the new 3.3 firmware, DON'T! You will lose some homebrew/hacking functionality. You can update via one of the modified firmware packages which can be found here in the forums. Do a search for IOS51 Shop Installer to find out more.