Do not know the answers but I do know some of them are found in this most excellent document on this topic, written by the Swiss government, and in English~!

It tells you how to claim back AHV and Pensionskasse, in other words both pillar 1 and pillar 2, and has all the scenarios spelled out.

See www.sbf.admin.ch/eracareers/docs/bff_englisch.pdf