What is the ruling on shaving the sideburns, and is it considered qaza' (shaving parts of the head and leaving others)? And is there qaza' for the beard by analogy with leaving the beard to grow as a Sunnah?

Shaving the sides of the head while leaving the rest is a form of disapproved Qaza' (uneven haircutting), due to the prohibition of the Prophet, peace and blessings be upon him, concerning it. Linguistically, Qaza' is specific to the head. It is not permissible to shave the beard, as there are Ahadith (prophetic narrations) stipulating the obligation of letting it grow.