You really should be able to use the XNA tutorials directly in your MonoGame development environment (whether that's Xamarin or Visual Studio). the biggest differences are up at the front (dealing with content, in particular) and once you're past that, most of the rest of the content should work identically between XNA and MonoGame.
There's not a schedule for new MonoGame tutorials. It's still a work in progress, and I've slowly been converting them over. But it does sort of come in spurts. Usually once I get on a roll, I'll convert a whole batch of them.
I'm actually pretty buried with some other things through the end of November, so I don't expect much work in the conversion area for the next couple of weeks.
However, I'm giving priority to MonoGame tutorials that need to be there, but aren't. If while following the XNA tutorials and pretending they're MonoGame, if you discover that something doesn't work like it is supposed to, email me or post here on this thread or something, and I'll try to get to it sooner, or to directly answer any questions you have.