1. As Mary says, it's not the intention. It's to provide course-based learning resources created by teachers delivered to students.
2. No you don't. It obviously (like any web-based software) takes a bit of skill to install and optimise (for live use anyway) but you absolutely don't need developer skills to use it.
3. I don't understand your question. In Moodle 3.2, if you want to find the code for the theme Boost, it is under theme/boost/ (in your Moodle install). Which seems pretty logical to me.
Having said all that - we'd be very happy to help if you have (more) specific questions