You just said "the winy taste", which actually means the same. It is not the same literal translation (word by word) even if the meaning is the same. I do often those errors.
Well, it doesn't really mean the same thing. You could like something that has a winy taste that is not, in fact, wine, such as over-ripe fruit or a candy.
Why guston de vino instead of guston da vino? Still getting da/de mixed up...
"da" indicates quantity while "de" indicates possession. Anything with "de" can be re-said in English with the possessive apostrophe 's'. In this case, it's "de" because you can also translate it as: "I like wine's taste." (This makes sense to an English speaker and shows that this is possession instead of quantity.)
Yes, because de already fulfills the role of the accusative, like french.