@lostwiiinspace,
1) the only way is by learning to code and modify the source code to improve it
2) assuming u are using configurable usb-loader and have ModMii's recommended cIOSs installed, just launch the game using IOS250 or 224. To get online u will need to create two profiles, then start campaign mode with both of them, then try connecting to multiplayer using both of them, and it will work on the 2nd try. Also, to get online u may need to update your shopping channel and launch it in order to accept the shop channels user agreement. If u've already used the shopping channel on your Wii sometime in the past, u probably don't need to bother with that. If you're using wiiflow, install cIOS249v19[57] and use it to launch WiiFlow and to launch the game (note that this IOS is not base 56, so it wont be able to play games with peripheral devices like guitar hero, for that, use either a base 37 or a base 56 cIOS)
3) try re-ripping the game, u may have a bad rip. Or, if a lot of your games freeze, you may have a sleep timer on your hard drive, u should disable that. You can also try defragmenting the hard drive, but unless its extremely fragmented it probably wont make a difference.
4) the SD card button on the main menu will change colours, lol. Seriously though, all it means is u wont be able to access apps saved on the sd card, if u save your apps to a FAT32 hard drive, u can access those apps from there instead of the SD card. There are only a handful of apps that ONLY work using an SD card and not a hard drive (ie. bootmii, sneek/uneek, mymenuify... maybe more I can't think of right now).
@Alexminator,
if u want to play backups from the disc channel, install darkcorp, but be sure to read the risks in the read me first.
If u want to just play backup discs without darkcorp or the disc channel, u can do so using NeoGamma or configurable usb-loader. I even built a neogamma autoboot mod so that when u launch the channel it will just automatically load the game without taking you to a menu (you can still access the menu by pressing a button after launching the app before the game loads). If you want the neogamma autoboot mod, check out my top channels page (links provided in the last step of all ModMii guides).