When you appeal you should be given a snippet of some things said that caused this. Keep in mind, what you see might not actually what caused the penalty. Also that masked language and toxic chat is included, it does not necessarily have to be completely vulgar to be against the rules.
Yes, they do have new rules in regards to advertising boosts.
Sharing accounts is not allowed, unless you are the parent of one child, but ultimately you are responsible for anything that happens on the account, it does not matter who is playing at the time.