v5.3-release-amd64 installation problems

[Marshall Kiam-Laine]

hi all :)  can anyone help newbie please :

(1) started with  fdisk delete all on HD, then  /mbr
      but it still picked up bootloader from previous attempt.
      how to wipe the HD totally clean first ?

(1) managed to get it installed, logged in, $startx,
      jumped to xterm, then crashed :
      "fatal server signal 11, failed to load  fbdev" = ?

(2) instead of startx, what is command to start gnome ?

(3) at no time did i see any option for 32/64bit install ?

many thanks !