c# environment

I am new to Ubuntu, but know c#. From what I have read, Mono will provide c# on Ubuntu.

Questions:
1) Is Mono both an IDE and a compiler?
2) What is MonoDevelop - just an IDE?
3) With Mono, will I have access to many of the .Net 4.X classes?

Leading to the last question: What apps do I need to install to in order to come close to replicating Visual Studio 20XX for c#?