There is a submit button under the main form... and a submit button under the options.
Threads and Events are different content items. Even if you approve an event, the thread may still need to be approved too.
Every event must have a venue / location... it doesn't need a GPS location though. But if an event doesn't have a physical location, you can put anything you want there. So if an event is on a specific website... list the website.
But again, why are there 2 Create event buttons, what is the purporse? They do the same thing right?