I'm not sure why they like it so much- it's definitely a matter of taste- I found little humour in it, but others may find it hilarious.
I don't think a bottle of vermouth would make it any funnier to me. I'd be curious to know what real drag queens think.
No one in the movie (besides the gangsters hunting them) thinks they're anything but women!

Very cool that you're checking out A Matter of Life and Death---that one is still on my mind. It's Magical.
Jack Cardiff's dreamlike cinematography is legendary. Did you know his own breath was breathed onto the lens to fog it up?