1) this all depends on what you want to do with it and if you can solder or not. I think there is a chart somewhere on here that compares all the kinds and features. The list can be found HERE
2) Isn't in a form of a question so dunno what to reply. However yes there are many emulators for the xbox that can be used. However legally you cannot have a rom unless you own the original game.
3) It is a 10GB drive, however only 8GB is shown and used in a standard unmodded box.
5) DVD2Xbox. Does exactly what it says on the tin (lol). Would need a larger HDD to do this with as you could probably only get 1 or maybe 2 games on the standard hdd.
7) If you wish to use xbox Live then you get a chip that you can disable, otherwise if you go online with a hacked bios you will be banned.
You will also need a bios for your chip. A chart to compare all the ones around can be found HERE
And to find most of the apps and bios's etc, that you will need you should check out this tut HERE