#1 u will need to obtain the 4920 dash from slayer's 2.5. search on google for it and u should easily find the bittorrent link for it. i believe bittorrent is the only way to get it. it's not on xbins.
#2 a memory card will work fine but then u will need to contruct an xbox to usb adapter so u can plug ur controller into ur pc. or u could use ur usb to xbox adapter and buy a usb jump drive look here
for a usb jump drive compatibility list. then u will need to use a gamesave exploit to gain ftp access to ur box. check my sig for my splinter cell exploit guide that has all the info u should need to get going.
#3 check on here on xbins /XBOX/exploits/Font_Exploits/doubledash/