In short, the lens names state the speed of the lens, the maximum aperture. A Summicron is always a lens with f2, a Summilux has f1,4 etc.pp.

Erwin Puts used to host a free (and limited) copy of his Leica Lens Compendium:
http://www.amazon.com/Leica-Lens-Com.../dp/189780217X

He removed it while he is working on a new edition, but Archive.org has it archived:
http://web.archive.org/web/*/http://.../llcforweb.pdf

It will help you a bit with your endavour.