A2-DB3150 Flashing

[karabaja2]

Ok, yesterday I debranded my C510 and changed the firmware using A2U and R1DA032_RED52 files.
My phone is CID 52 and so the question is this: Can I flash it using the newest R1HA035_RED53 since it is for CID 53? Generally is it safe to flash CID52 phones with CID53 files, and 53 with 52?
I think this firmware is older than the one I had before flashing but i don't remember which version was before...
And when to apply Custom files? Before I turn on the phone after flashing it or to let it first start and then turn it off again and add custom files??

edit
And what would happen if i combined different FS and MAIN files? For example C510_R1DA035_MAIN_GENERIC_KT_RED52
and
C510_R1DA032_FS_CENTRAL-EUROPE_RED52

Thanks!