I believe that belly describes the outer surface, while stomach describes place inside the body. That is why you always say "belly button" and never "stomach button".
But a person can have a belly ache which is the same as a stomach ache. Also the Danish for a "beer belly" is "ølmave", in this example belly is the direct translation of mave.
The above translation says stomach but the translation I was originally given was tummy which is a very childish term.
"Gammel" becomes "gamle" when it's in the definite and the plural. :)
Den gamle mand
De gamle mænd
En gammel mand
Et gammelt hus
Yeah, adjectives all decline, but often in a more predictable manner than "gammel" -> "gamle" (the adjective I was describing).
Does not the word "fuld" in this context imply he is drunk? I would use the word "maet" not "fuld"
Fuld means just "full" if it's not talking about a person. A stomach can be fuld (physically filled), but only a person can be mæt (not hungry).