Hi. I am very new in forums and I need very basic questions

Hi. I just saw you when trying to make fun a z170 mobo with coffee lake…
I read a lot in forums, but kinda I am lost as the beggining.
My bios programmer will come kinda 3 weeks
So, I need a bit of of questions be asked, very basics, but the forums are too big that I am not so sure where to begin
1 may be with bios mod a sky kaby mobo can run 9nth gen?
2 very specific, does gigabyte sniper b7 can be flashed? Any sucessfull history with that mobo? (I am just reading a gigabyte thread)
3 if I got a mistake when flasshing, maybe I am safe if I reflash with the bios programmer from other pc?
Thank you very much for all responses