Küche vs Essen - "cuisine" is better/nicer sounding when talking about the category of food overall?

"Danach haben wir vietnamesischen Kaffee getrunken." -en because it's plural here?

(1) In general, I would recommend against overusing the word "das Essen", at least if your heart is a bit on the "gourmet" side. When the you cook at home and call your children with "Das Essen ist fertig!", it's perfectly fine. When I talk about a simple, inexpensive restaurant, I can say "Das Essen ist dort sehr gut". If I feel that it is a bit higher level (linen table cloth, a reasonable wine list, ...), I would say "Die Küche ist dort sehr gut" or "Die Gerichte sind dort sehr gut". When I talk about the typical dishes of a nation, instead of concrete dishes made by a concrete cook, I always use "Küche" (general) or "Gericht" (refering to specific dishes). For instance, the English term "national dish" is in German "das Nationalgericht".

In your case, "Küche" fits best, because you are talking about several countries ("alle anderen Arten")

(2) No. It can't be plural, because this would be "Kaffees".

It's the declension of adjectives in accusative.

Example: "schön"+"Hund"

nominative: der schöne Hund / ein schöner Hund
accusative: den schönen Hund / einen *schönen* Hund

Thank you! I understand about Küche vs Essen now, and also thanks for explaining Gericht, I saw that word when looking up options but had never seen it used so I wasn’t sure what to do with it.

Yes of course about Kaffee, I think I had just stared at the various adjectives in this one for so long I forgot the basic one there. Thanks!