Default 2 questions regarding flashing firmware

hi guys i just have 2 questions regarding firmware flashing. I know i can use flash tool to update my phone to 4.3 but when i flash do i have to do any partitioning and that stuff or do i just have to put it into fast boot and flash the rom? secondly will i loose all data if i flash the phone? whoops i lied i have 3 questions does anyone have the firmware for the LTE C5306 Xperia sp Canada version, i guess thats the north american one. Thanks in advance guys
current devices:
Xperia SP
Xperia J (x2)
Nexus 7 2012
iphone 5
iphone 4s
iphone 4
Htc 8s
Lg l7
Lg optimus G