No, only if they are region free, if they are NTSC/J, then no.
There is no way (worth it, too much trouble to go through and way too complicated, this also works only on the very first Xboxes, those without HDMI and you would stay in Japan region code).
Yes, you can.
Xbox 360: Slim untouched with a faked 320 GB harddrive for XBL, phat with LT 3.0, played Halo early, so going on live would be an instand ban, also with a faked 320 GB harddrive
PS3: Untouched 160 GB Slim, 60 GB Fat with latest Rogero and 160 GB internal harddrive.
PSVita: hardly ever play it
GameCube: Black with a Viper chip installed. With gameboy player. Trying to get a Wavebird controller.
Come talk with us on efnet at #elitemods !!! or just click ME
ALSO, DO NOT SEND ME MESSAGES ON LIVE REGARDING MODDING CONSOLES, OR HOW I PLAYED A CERTAIN GAME EARLY. I WILL NOT RESPOND. I WILL INSTEAD DELETE YOUR MESSAGE, AND BLOCK ALL COMMUNICATION FROM YOU. JUST SEND ME A PM ON HERE.
It is impossible to be banned if you are offline. Consider having any type of internet connection on the xbox as being on LIVE. Whether you play people or not, they still get your info if you've got a connection.
Whether you would be banned for playing offline is a hard one to answer more so if you used the original disc for the setup & not the copy & that includes the usual update thing the very first time you logon,it also would mean there would need to be some sort of change when gaming offline with the copy that would rewrite something somewhere either in the update or the game save,i highly doubt if using the original disc getting the updates & using said original will get you banned,if you were it would mean the game save is how they would detect you had a copy of a game & that includes using original disc to install to hdd.
Just for the record the above is how i do things,use the original for setup & updates & (install to hdd depending if it's a game i would play more than once) tho i only had a gold thing for a month,i used original discs at first then used copies to see what would happen,nothing did & now i'm back to silver all i do is use any new games that i get to get the updates & game save setup on the hdd & any freebies to download,all's fine for the last 6 months,HOWEVER it would be best me thinks if your were into gaming online to have two consoles one for online & perhaps unmodded the other for offline & modded,tho even if you did have a modded online console so to speak but never used copies you should be fine since DVD-ROM BIOS hacks can't be detected from the xbox os or even recorded by it,unless someone can correct me