I've had a beard for the last 35 years or there about, so I'm not going to shave it off just to sing. I think the Guiness is a throw back to when the "Big 5" had control of the swill that was sold as beer back then. Guiness was at least consistent and once you develop the taste for it you are hooked. I do prefer to try any "REAL" ales that are on draught though "thank God for CAMRA".
I don't speak the last lines as I find it a bit of an affectation, I do however on occassion toast the writer of the song at the end, as in "Scowie". I often find I have to close my eyes to concentrate on the words and the song in the hope of not screwing it up.
I only sing in a tuxedo whenI sing with our local community choir.
I think your description fits more of the so called "revivalist" class of singers than the 20th century source singers.
JohnB