Well, basically, the question is this: do you want to focus on making your drawings more realistic, or on improving your skills as a cartoonist and caricaturist? Personally, I think it's a good idea to do a bit of both - realism is great, but being able to slip into free-form bigfoot territory can be a useful skill. (What if, for example, you wind up working on a Mr. Mxyzptlk story one day?)
The former. Nope*. Probably never happen and if it did I'd draw him as a flying dwarf.
Yep, Barks is master of storytelling, and I truly enjoy his work. I'm also a big fan of Joe Sacco, who uses that sort of cartooning to devastating effect as a reporter.
*I'm a bit of a fanatic when it comes to realism. Cartooning is nice and I have some friends who are very good at it, but that is not what interests me personally. Except in rare cases like "Sita Sings the Blues" I am not into the abstraction of the human form. Other people are welcome to strive for what they want to strive for, that's just not what interests me.