Hopefully getting a 360 soon, need pointers

hi guys, i need to know some things before i get my beloved xbox 360, all in a line :-p

[LIST=1]
[]can i use my old xox live account?
[
]Do you have to pay an additional cost for some xbox live games?
[]Do i HAVE to use my HDTV?
[
]Is there a CHEAP wireless adapter somewhere?[/LIST]Thanks for replying!