DodgyPutter: There is no set time for the former I'd have thought they'd give some indication but it seems not.
AFAIK, it's about 25-30 posts, but they don't keep records. Therefore, it's good for new users to make themselves known by frequent posts and to knock at the mods' walls.
Not sure if a "+1" will help though.
One downside of moderation is that the post is published late but with it's original date stamp. Thus, it has a good chance to disappear from our view in the pile of unmoderated posts. I'd appreciate if the moderating official would take the time to answer to questions while releasing them, but this ain't happening AFAIS.