I've added a feature request in the project tracker for showing the tickets sold vs available and a link to view orders on the event edit page.
I want to reign in your expectations a little about the idea of custom user input for event registration. In the not too distant future I think you can reasonably expect to see a free form text area and a custom instructions for what the user should enter there. Longer term if I can figure out a good way to do it I am pondering some integration with Form Wizard Pro not with the free survey feature included in mojoPortal, and if I'm able to come up with a good solution it will involve detecting if Form Wizard Pro is installed and it would only work if Form Wizard Pro was installed. Its a fairly tall order so I'm not making any promises about it for now other than to say I'm pondering how to do it and I do see the value it would add if I can pull it off.