Migrating from VS 2005, how hard is it?

Hello, I have some applications that were made with visual studio 2005 and use extensively CR reports forms.

First question:

What does it means that VS 2013 is not supported?

- The aplications will not compile?

- I can't create new forms?

- will I have have to use VS 2012 until 2013 is supported?

Second question:

Will I need to do many changes in each report or CR 2010 for VS Studio is backwards compatible?

Regards

Gerardo Huerta