I have just finished reading "The Reluctant Widow" by Georgette Heyer, and found several words/usages new to me. (It takes place in England, during the time of Bonaparte.) Can anyone explain any of the following?

-In the coach, she leaned back against the "squabs".
-When someone died, there was something called a "hatchment" put up over the front door.
-One of the servants was an "abigail".
-One of the (native to Sussex, I believe) servants said, "A dentical fine gentleman".
-Someone had gone to the "Peninsula".
-The old servant couple, fussing at each other, would say "Do-adone", or "Adone-do". (Hmm-be done with you?)
-I got that this meant telling a lie or a trick, but why "gammon"? (As in, "I'm not gammoning you.")
-What is a glass of "ratafia"?
-He wore very tight "inexpressibles" (no further hints).
-They had a "nuncheon" of cold meat, fruit and tea. I like this word! 'Minds me of "nuncle"!