I managed to get Monogame runing with my code. Thanks to c# defines i can use the same code to compile on different IDE (Visual Studio 2010 & MonoDevelop) for 4 different platforms. Windows XNA, Windows Phone 7 XNA, Linux Monogame, MacOSX Monogame and even Windows Monogame (i think XNA should do it).
Here is a video of Farseer Physics. I had to integrate ConvertUnits and now everything is scaled correct. If you have problems take a look at this blogpost.
I reworked my gamedesign. Yep, collecting diamonds is boring. Now i want todo a variant of snake using physics. Same style but ... stay tuned!