I turn it off all the time and it's safe,my computer still running fast and no virus came in.
But its better if u just turn off ur anti virus everytime u play the game or just add the game as an exception.
AFK = Away From Keyboard
Theres a lot of words that they used to call items or equipments that has long names.You can find that a lot at the MarketPlace(NH 3)
Just search it on the internet,first remember the symbols and sounds like learning ABC..i already remember all of it but u will need to remember and know some of the basic words too.