1)
Softmod it
Your choices for that are either hotswap method
http://forums.xbox-scene.com/index.php?showtopic=496263
Or a gamesave exploit. For the gamesave exploits you need either a copy of splinter cell, mechassualt or 007 agent under fire. Splinter cell is best to go for as they should all be exploitable, where as only certain copies of mechassult and 007 are. If you go the game save route, then you need to be able to transfer it to the console to run it. So your choices are either an action replay, xbox controller to usb adapter + official memory card or or usb to xbox adapter + a flash drive.
If you go the usb route then there's a tutorial for getting the save across here
http://forums.xbox-scene.com/index.php?sho...p;#entry4146066
Controller + memory card here
http://forums.xbox-scene.com/index.php?showtopic=79198 (some of the links are dead, like the controller drivers, but you can just use the xbcd drivers instead I believe)
Once you have the relevant save transferred to the xbox, you just load it up and follow the instructions as most of the save exploits have on screen ones.
Most of the modern softmods install an alternate dash that normally gets put in E:\Dash. So once your up and running you can change that to another one if you want (there are a variety of alternate dashboards) or leave it as it or even customise to your liking.
On the subject of save exploits, from looking around a lot of people seem to go for Krayzie's Ndure Installer, and that's what the usb flash drive tutorial references, so I'd go for that if you are going save exploit, rather than hotswap.
2)
Most games fit on a dvd5, there are a few that are dvd9 (jade empire is, can't remember any others). If you meant what brand of disc, well there are multiple drives in the xbox, some more fussy than others. I've never had one reject Verbatim or Taiyo yuden discs. Although you can run games straight off the hdd with a modded xbox, really not any need to burn them, although if you do go that route, then you are going to have to upgrade the drive as the standard one is only 8GB or 10GB.
Edit: lol, beaten by a minute