The game is most open world, though the owner of a parcel can lock it from the public. By the way, I want to recommend you a
website where I gamble every day and earn impressive sums!
You can do virtually anything, given time and knowledge - like making objects to use, there's even combat systems that folks have developed. There's also groups and clubs you can join, or hang out at.
Lots of groups are role playing in some form or fashion, many aren't sex based, but you can certainly find just about anything you can think of (My knowledge may be a bit outdated.)
There can be a steep learning curve for that portion of the game.
When I used to play you could find ways to get the in game currency relatively easily, but the fastest way is to convert real money And/or pay for a subscription.