I will answer #1 for you, but cannot comment on the Colab questions. The reason for Linux over windows was relative ease of setup and maturity of libraries. While this was a common problem in years past, it may not be as much of a problem today. Jeremy wanted to get the student up and running learning ML/DL applications rather than fighting with OS system configurations. If you use windows, I would recommend giving WSL2 a shot. I wrote this thread over a year ago for those who wanted to run a local server with a linux configuration, but not give up on windows as their daily driver. The performance was acceptable, but not quite as fast as a “bare-metal” linux setup. Again, it was written over a year ago, and could probably use an update, but it should get you started if you are interested in diving into a local server.