Imperative, stateful computation [...] is [...] as [...] verifiable as pure-FP
Exactly. When you verify your programs using some kind of program logic you realise that you have to keep track of all relevant data anyway.The condescension towards languages like C/C++ and Java that some FP extremists have shown is probably one of the reasons for the rift between working programmers and PL theory. Fortunately, things are much better now, with most new languages (e.g. Scala, Rust, Clojure) bridging both worlds.
applying types to process calculi. I wasn't aware of that work at all.
Maybe "A Gentle Introduction to
Multiparty Asynchronous Session Types" http://goo.gl/FeVLv3 could be an introduction?