-terminate switch terminates the X Display when there are no applications running anymore. I don't remember what -ac does anymore but it's in man page. About the sound issue. You are probably using distro that has sound configured wrongly, or it's pulse audio issue. I'm using Arch Linux and Alsa, and stuff works fine. eg. In old linux mint I once had, you have to be root to play any sound when switching to TTY terminal, which is bad.
