I worked as a software engineer for well over a decade before I got my degree. You can learn everything you need to know without a formal education. However, if I was hiring, all else being equal, I'd choose the candidate with a degree in a heartbeat. Mainly because it demonstrates excellent self-management skills. Especially thesis writing is extremely challenging for most.
Are you talking about your PhD? As I understand it, most CS bachelors students don't write a thesis (or theses).
No. As a consequence of the Bologna process all cycles of higher education (Bachelor, Master, PhD) ends with thesis work in most European universities. However it is called different things on different countries. Diplomarbeit in Germany, mémoire de license in France, etc.