s-off, root & custom rom vodafone contract topic

hi everyone just a couple of questions for you

1. is it possible to get s-off on uk vodafone contract phone?

2.what is the procedure for s-off for this provider locked phone?

3. is there a stock image for me to revert back to on vodafone uk contract phone?

i really wanna try different roms with this phone but more worried about warranty and flash counter etc voiding the warranty

help would be extremely appreciated if you need any details of the phone dont hesitate to ask for them, build number etc