if u know how to flash using odin,then i say that flashing using kies is useless.u should just flash by odin in the beginning.

and this is what people usually do when we have problem flashing with odin - reflash the firmware back(twice or thrice).most of the problem solved this way.

instead of flashing with dxkb2,u can try flash from beginning with latona.pit and then proceed with xxkb3.flash xxkb3 twice or thrice(with not flashing latona.pit again).enter recovery and factory reset+wipe cache and check the functions back.see if the buttons working or not.
when u found that those buttons working,flash ur desired firmware(dxkb2,dxkp9 etc).but make sure u check those function working in xxkb3 first before proceeding.many people succeeded that way.

hope it helps

try to flash to dxkf1 first. then using the same latona flash to dxkp9.

there is a mod in xda forum for that,but ur firmware should be xxkpm.if ur on xxkpm/kpn/kpq,u can try that mod(its for camera,donno for music player)
http://forum.xda-developers.com/showthread.php?t=1323932
try flash from latona.pit,dxkf1(twice,thrice until the button working)then dxkp9 via ODIN
theres a mod done by somebody(i forgot the name,bcoz i use the swap thing    ) he makes patches for gamelofts so that u can change the apk to install data on external sd.he creates for both lg and samsung devices separately.u can search on google and mobilism.org. but there is a bug,where some people say when they patch apk of a game,they get a file of another game eg:u make patch for asphalt 5,u get fishingking 
u mean by available internal storage is phone storage or internal sd storage?