A lot of the methods used to obtain accounts are illegal in the first place (identity theft, identity fraud, etc.), so I'm sure letting someone else use one would be no problem, granted you're okay with the way you got an account in the first place.
There are no up to date guide threads for settings, however I believe somebody posted a translation/guide in an old KR Update thread.
Use the search function to find more answers, and use the General Q&A Thread next time you have some questions