Welcome to Python!
To get started with python, you probably want to know some basic python. Codecademy has a good intro that should be able to get you started.
Here are the instructions for everything robotpy.
In terms of being recommended, it depends who you ask. I would say go for it! If you don't like it you can go back to one of the official supported languages, although it's on par with them.
Stable...hmmm.....sure

. It's pretty reliable. Thing were a bit shaky around kickoff but as of right now it should be smooth sailing. And if you ever run into issues, feel free to ask here, or on the robotpy
gitter. It's a pretty active community and you'll get a response quickly (probably faster than CD).