Is python a good programming language to start with while learning CS?
It's a perfectly good one, yes. Python is relatively simple and reads about as much like English as any language. It's not perfect for everyone -- no language ever can be -- but it should be a great start for most people.
How do you suggest I use the MIT OCW materials? Read first and then watch or the other way around?
It'll depend on what your learning style is. I'm more of a read-while-doing kind of person. I use the videos to double-check that I didn't miss any concepts.
How can I test the programs I develop? Do I need to buy a Python widget?
There are free programs that help you develop in Python. There are links to some in the course materials.