You would do this with web apps.
When logged in you can submit web apps. So you can use the Web app add form and make that nice and allow them to add them.
You can also pull a list of web app items belonging to a person when logged in and allow them to edit these too.
Being web app items you can then use the list layouts etc to show them on the actual website. You can also set these to need approval before they go on the website in the webapp details page when you build/edit a web app.
To reply to the event you would use comments.
Without this and if you have bookings or not all you can do is have a web form, take in requests and manually add it into a page / announcement or what ever and then have comments on that.
