Basically we need a website like [login to view URL] website. The basic appearance will be changed later and some functionality as well. The website is supposed to be built on bootstrap, jquery, php. You can use a custom cms or one of well known cms.
Only one language will be used.
Facebook and email registration/login will be used. No other methods.
Some functionality could be simplified.
Some content can be static and changed only in files, for example the menu.
Supposed to be as much simple admin as possible.
The functionality for users is not that big - people can register. They can add their events, set the date, people number. They can attend to other events, get a confirmation if accepted to participate and then unlock a function to chat with other members on that event. So some kind of simplified chatroom plugin would be required.
Please browse the website to see more details. If any questions, please ask.