i don't think singles should be able to go out if there's someone to pair you up with... if nobody else is around, then why not let a single go? it seems kind of ridiculous to make him wait in the event that someone else comes along...

i also think it's perfectly acceptable to play 2 balls as long as the course is pretty empty when you go and you're not holding up play... really, i can't see the harm in it but every course has the right to make their own rules... that's still not to say some rules are often ridiculous...