I have seen many papers and patents in which thermosetting siloxane plymers were reported. Please see the paper which is attached. That might be useful for you. There are many reports in the literature concerning your second question. In this regard see the following paper:
Linear siloxane polymers as precursors to high temperature materials Author:
Son, David Y, Polymeric Materials Science and Engineering, 1994, , 71, 305-306.
You can also have a look at the papers: Son, David Y.; Keller, Teddy M. From ACS Symposium Series (1995), 599(Fire and Polymers II), 280-90. or Son, David Y.; Keller, Teddy M. From Polymeric Materials Science and Engineering (1994), 71, 305-6.
but since I was not familiar crosslinking resins siloxaniche, I do not know
The siloxane resins in which temperature or pressure which will thermosetting character? can you explain me more about this page (polySilsesquioxanes Solid T-Resins) ? Whats their solvent?