Best XBOX Softmod

Hi, across the net ive seen many different XBOX 1 Softmods, ndure exploits, auto installer deluxe, mechassault/splinter cell/007 exploit.

Im starting with;
A sealed XBOX
250Gb HDD

Any im going to purchase a memory card (actually a USB to Controller lead so i can use a USB Key as a mem card). If need be i can get one of the exploit games.

My question is

  1. Whats the best way to softmod an XBOX of all the guides on the internet, ultimately id like to have XBMC on there
  2. With the 250gb hard drive, is there anyway to use this while on live ie if i install it before going on live for the first time so it ties the EEPROM to the new HDD?