Language and compiler depend entirely on what you're attempting to accomplish. I would suggest, though, that you might be approaching the problem from too low a level.
There are materials out there on operating system fundamentals. MIT has OpenCourseware on the subject. Read through Andrew Tannenbaum's Operating Systems series, and look at things like Minix.
Get an idea for what's out there. Start tinkering with things. Borrow ideas, and see where they go. You can reinvent the wheel if you really want, but you'll learn more by building on the works of others.
