This verb apparently has multiple meanings, so you should rely on context when translating it. In Bulg. for example гуляя (1 sg, present tense) may also mean 'to feast' / 'to celebrate rampantly' / 'to get severely drunk' / 'to tear animal's skin', etc... Most likely, the original meaning is the last one, because гуль- makes an ablaut pair with жуль- ('to scrub, rub'). Note that a similar semantic shift happened with the Germ. spazieren ('to go for a walk') < Lat. spatium ('span, spread').
Куди means "(to) where" (direction), де -> "where (at)" (location).
"Where do you like to take a walk to?" sounds strange. Usually, when one takes a walk, one doesn't go anywhere in particular, but is just strolling around (hence, the location question, not the direction)
"Гуляти" means "to dance" in Ukrainian. I believe this 'modern' "гуляти' term came from the overuse of Russian within Ukraine when it was under Soviet occupation. "Гулять", IN RUSSIAN means "to walk"..... Let's correct the Ukrainian language to its 'former linguistic musical glory' and find and use the beautiful 'old' words and make them new again.
By Ukraine being in the Soviet Russia orbit for so long it's not surprising the language has some Russified words. It's high time to change that.....
Hrinchenko's dictionary, which was made before the Soviet rule, lists 'to walk' as the first meaning of «гуляти», and 'to dance' is only mentioned at second-to-last meaning. So, this meaning has nothing to do with Soviet times.
What you're advocating is not a return to old words, but a replacements of Central and Eastern Ukrainian words with Western Ukrainian words.
This course is no place for such advocacy. This is a course of literary Ukrainian. If you don't like literary Ukrainian, and want to use Western Ukrainian, then this course is simply not for you. You can suggest a creation of a Western Ukrainian course in the Duolingo incubator: http://incubator.duolingo.com/