Hey there! If you have bought the game after beta, there isn't a mandatory subscription anymore so you can hop in and try it for yourself if you wish.

Anyway, the max VR is VR16 right now but that may change. ZOS stated several times that they intend to remove the Veteran Ranks eventually, but before they do that they may raise the cap again.

You were never really required to do other factions to gain Veteran Ranks, as you could level up in Cyrodiil instead. A DLC scheduled to be released next month will add an area accessible by characters of any level and that will scale you while you are there, so I assume it will be a nice place to level up too. There is Craglorn too, but that zone was tailored for group play and can be really challenging for someone playing solo and on their early VR levels.

You get battle leveled when entering Cyrodiil, but a fully equipped VR16 will still be much stronger than someone that just jumped in. There are also Champion Points now to consider, which are a different line of progression. You start getting them when you get to VR1, and you can apply them to all the characters in your account. Here is an explanation on the new system. Anyway, I find non-VR PvP much more interesting and fun TBH and I almost exclusively PvP with my low level alts in the non-veteran campaign, Blackwater Blade, instead of with my vets.

And that's not a lot of questions actually. Feel free to ask anything.