The fist option is very important as I don't believe anyone will sell tickets if the audience can see how many are remaining or more importantly how fast they are selling. I suggesting the ability for users to not publicly display the quantity remaining. Similar to how Ticketek does it. Only the people who post the tickets can see quantity remaining.
Also Chuck. I'm going to give your efforts on Classifieds a mention on my blog at www.joshuavanaalst.com
. Should be up shortly.