Gonna correct you a bit here.
- With a catch they are. ERP events cannot be made public. Yoshi P already said before that he does not care if you ERP in private. You just cannot advertise it in public game channels, or make it public. See this old (but most recent on the topic) article if you want to know what ERP is allowed. https://www.gamepressure.com/newsroo...private/zb3bae
- WRONG. It is not against TOS. See above.
- Correct. Keeping your age group above 18+ is a good way to protect yourself from accidentally getting involved in any inappropriate conduct between like minded adults and minors. Of course that doesn't mean they won't be randomly added in duty finder, but as long as you keep your conduct correct in those instances, then absolutely.
- This is a gray area. While it falls under third party tool regulations, SE has made little attempt to vocalize any disdain for aesthetic mods other than that they do not like seeing adult screenshots shared on public channels. I highly recommend never sharing these publicly, or putting a name attached. For one, it respects the game developers. If this game were to suddenly have adult screenshots shown in a search engine, some people might get the wrong idea of the game. Say a parent wanted to sign up their kid, it might be what would scare them off if they were none the wiser.
I suspect that in the future when the game has its 7.x graphics and texture upgrades, that they will begin to make firmer stances on the rules for aesthetic mods. Shaders could for instance even suddenly get banned outright completely, with a wave of warnings, and bans to follow. I would watch for this if you are a fan of such things. I play on console, so I don't have access to any of these, or need to worry about it.