Re: Odo: trying to eat and drink...
addresses this after he becomes humanoid. He has a whole conversation with Sisko about how he doesn't get as much enjoyment out of his job, but he loves to eat. So Odo, not as a changeling, has experienced food the way you and I do.
"Cogley was old-fashioned, preferring paper books to computers. He had an extensive collection of books, he claimed never to use the computer in his office."