plex pass

I don't have plex pass yet , thinking of doing 1 year or lifetime,
Question 1- plex pass gives me use on all my mobile devices,
2- Download the plex app for window Pc - Tells me to activate- need plex pass? I like this better than Plex theater!
3- With plex pass ,and creating home, my phone connected will be backing up photos, if create an account for each member in home, will there phone be backing up in a different location than mine?? Can I see there stuff, but not them seeing mine? how does it work?
4- Is the phone photo duplicating picture still happening?