Windows is fine for development. Tons of people do it, it's just not hip & trendy on hacker news. Don't waste time on learning a new OS if what you really want to learn is code. Both PHP and Python have first-class support for Windows, and so do most other tools (databases, webservers, etc).
Best way to learn is just by beginning. Set yourself a relatively modest goal. It can be useful even if it's modest. Something you need, maybe for yourself, or for some community you're in.
What you say is true, but I think it is worth mentioning that majority of hosting for PHP will be on some kind of linuxy/unixy system so familiarity with that won't hurt.
Best way to learn is just by beginning. Set yourself a relatively modest goal. It can be useful even if it's modest. Something you need, maybe for yourself, or for some community you're in.