The issue of being a "completist" in the terms you've defined is still difficult to answer, I think. Lucasfilm doesn't consider the Ewok films you mentioned (nor the Droids cartoons or
The Holiday Special, for that matter) to be canon, but
Star Wars: The Clone Wars (CGI movie) and
Star Wars: The Clone Wars (CGI series) are considered canon. So, are you concerned about "completion" in that sense - i.e., the official categorization of what is and is not canon? If you are, then, yes, both are required in order to meet your goal of completion.
If, however, you're simply interested in completing your collection and viewing experiences in terms of what's
good and therefore worth your time and money, then my opinion is thus: Skip the movie, because it's crap. Watch the series, because it's pretty darn good.
I have a question about that...I see on Netflix, there's a
Clone Wars Vol 1 and 2, and a
Clone Wars Season 1 and 2. I thought they were the same but the "volumes" are a collection of animated shorts. Do they meld together into a coherent storyline? Which do I watch first? Why is this so confusing!

Only
Clone Wars Season 1 is out - is that chronologically the first part of the story?
Here's the thing,
Temis. There have been two separate series based on the Clone Wars. The first (
Star Wars: Clone Wars) ran from 2003-2005, was under the direction of Genndy Tartakovsky (responsible for
Dexter's Laboratory &
Samurai Jack), and was referred to as a "micro-series." It was initially a series of 3-minute shorts (season 3 changed to 12-15 minutes) that aired in between normal-length episodes of other series on Cartoon Network. That series would be the Volume 1 and 2 sets that you're seeing on Netflix, and I thought they were damn good.
The second series (
Star Wars: The Clone Wars) kicked off in 2008, with the theatrical release of the same-titled movie. When this series was first getting off the ground, Lucas referred to the Tartakovsky series as "the pilot series" - it basically tested the waters, although the two series have drastically different art styles. This series is under the direction of Dave Filoni (previously worked on
Avatar: The Last Airbender). You've seen some of my thoughts on this series in another thread already, so I won't repeat myself here.
I don't believe that
Clone Wars is available through new retail releases any longer. When I wanted to purchase the two volumes a few months back, I had to buy them used but it was so worth it to track down. As far as melding into an overarching storyline goes,
Clone Wars does chronologically take place prior to
The Clone Wars, though TCW doesn't always move forward chronologically even within its own series. For example, there's an episode in season 1 ("The Hidden Enemy") that is actually a prequel to the movie. I do not believe, however, that there are any contradictions between the two. I have watched CW then watched some TCW episodes directly following, and it does feel like a progression for the characters. Anakin becomes a Knight, for example, in CW and takes a Padawn in TCW.
Looking back over this after typing it, I'm not entirely sure how clear I'll be to someone who doesn't have access to my mind to know what I was thinking as I typed

but I hope it's helpful.