Macbook Pro Retina 2013 - icloud? serial?

Hello guys,

im new here and i have few questions.
i had read the efi chip 5 times now, and the md5 check passed.
i was a bit orientated on your "Mac Unlock EFI Password Part 3 of 3 - Flashrom & Password Replacement" Video.
i must say i dont use the raspberry variant.
i use an TL866A with an soic8 Clipper.

however, now i have erased the $SVS part, and im about to Change Serial (if possible) and Change icloud.

so my question is:

1) is it possible to alt one number or letter of the Serial and that it still works?
2) in the Video it is shown to use an external drive, install with new icloud (own) account to override the old credentials.
isnt it possible to Change the credentials under the icloud part in the bin file? the email, Name etc. can be found easy in unencrypted.

thank you!