formal verification is a very important tool.
What are the major differences between
Promela,... and their pro's and con's for what specific usage cases? What do you think about graphical representations of communicating systems (
v-Promela,...)? What other lesser known/used
process calculi do you recommend?
Is your question regarding the verification of cryptographic protocols or protocols in general?
I do not know much about the field and cannot answer all your questions. I do know that applied Pi calculus is quite popular for cryptographic protocols (especially in cryptographic voting protocols) and the ProVerif tool is often used.