Can you do AFK farming in this game?

Yes you can since the game has auto-combat from the start. However, watch out for your device's battery life (not an issue if you're playing on the PC via client or emulator) and if your character is strong enough to keep himself/herself fighting alone.

Are they not kicking us into the game whenever we afk and farm for too long? it happens to me, theres something on my screen if i afk too long and i need to swipe the bar thing so i can actually go back to the game.