What is the shirk of the self (shirk an-nafs)? Does it include abandoning obligatory acts or abandoning supererogatory acts due to laziness? Is every sin committed considered part of the shirk of the self? And is it minor shirk or major shirk?

Following one's whims can be major shirk, minor shirk, an innovation (bid'ah), a major sin, or a minor sin; what determines this is what these whims lead to. Every sin a person commits falls under the category of following one's whims. Disobediences can be generally referred to as shirk in the sense that they result from following one's whims.