A modchip (acronym for Modification Chip) is a hardware chip that has to be installed in the Wii.
By doing this, your wii will be able to play disc backups (both Wii and Gamecube in most cases) from the disc channel at full speed (6x).
The only advantage over a softmod is that the games will read at their normal speed (6x) instead of half speed (3x) for backup launchers, and its 100% compatibility.
But even so, this is not a really big advantage
The newest modchip is called the WODE jukebox, which can play Wii and gamecube backups from Disc and USB (making it the ONLY way to play Gamecube games from an HDD).
Will this guide work with modchipped Wii's?
Will the modchip conflict with some of my homebrew.
A modchip will not conflict with ANY homebrew.