wiikey: it is designed for all dms,d2a and d2b wiidrive chipsets
yes the modified wii can go online but be very cautious
wii firmwares/updates, is just basically little software tweaks for the game to play properly, but cross updating the system (i.e updating the system with a pal update on a ntsc-u system or vice-versa can result in a bricked system)
wiiware is little utilities for your wii
why some game will not work cause of multiple reasons, (if your wii is modded and you attempting to play backups and it is not reading, the type of media you are using, what kind of burner and software you use and how you configure your pc)
now the modified wii can play both ntsc an pal games, for the wii to play pal games on an ntsc systems you need to patch the game iso using region frii for the game to play without the screen rolling or showing in black and white
now modchip firmware updates is very important for all nex-gen systems cause remember the manufacturers who makes the systems and games will do anything in their power to stop people from modifying their product (in their dreams) so whenever they release a game title with an update or a system update to detect any kind of modifications done to their system the modchip makers will have to work hard to make an update for their chips to cope with these security issues and whatever chip you bought you will get the updates right in the website or you can get them right here. whoooo now that was a mouthful but I hope I answered your questions.