[m-ou-se]

It doesn't translate Python to Rust or anything like that, it uses CPython both to compile to Python bytecode and to run it. It doesn't launch a separate interpreter, the interpreter is used as a library, so runs in the same process.

Python doesn't really do multithreading: https://wiki.python.org/moin/GlobalInterpreterLock

It uses Python 3 of course. Using Python 2 these days would be a crime.