Pronunciation

Neither unless I was being careful. (UK RP speaker.) The second n in environment was some horrible and unexpected surprise I came across in a school lesson about age 12. It was several years before I reliably remembered to include it in the spelling of the word.

I nearly always drop the d in sandwich but in Ireland you can hear it turned in to a g as in sangwich.

Could I have a hang sangwich please. Or just a sanger.
Usually drop the "N" from environment too

My Australian grandchildren ask for "samwitches".

Vulnerable seems to be the most mispronounced word ever. Radio and TV announcers always say VUNerable. Ugh!

In Manchester, a sandwich is a "Butty" - and a bread roll is a "Barm".
BBC TV Commentators still say (during athletics programmes).... "The" Ukraine.

Yes to both - all 'd's and 'n's are accounted for. I say en-vi-ern-ment, as well. I just tried it without the second 'n', and it sounds totally weird coming out of my mouth.

I'm watching a DVD of Ghost Writer in which Kim Catrell is using a posh English accent and she said there are san wiches in the kitchen. I replayed it to verify it, but she didn't pronounce the D.