I didn't know there were such things as rewritable dual layer DVD's, if you mean DVD+R DL, then yes they are the only discs you can use to backup your 360 games.
As for best drive to make backups, I will assume you mean burn not rip, any drive that supports booktype changing to rom, although you don't need it anymore it is better if you plan on connecting to xbox live, if it was ripping you ment then I would suggest buying an Xbox 360DVD drive that you can install on to your PC. You can buy them from www.ck3.co.uk they are under £30 and I would choose the Samsung model TS-H943A MS28 as it is easier to connect and flash, you will need to flash with a 0800 firmware.
Use xbins to get all your programs and tools, and read as much information on this forum and others, use Google, eat your greens and don't piss against the wind .
Yeah use an Xbox drive to rip your games as kreon flashed drives don't get SS v2. And download easy xbins to get the program for ripping Xbox Backup Creator is what I use.
