Hi skeplin! Welcome to Line of Action! :)
Your characters look pretty good, it's a pretty adorable cartoon style. I like it!
If I'm understanding you correctly, you want to learn anatomy and how it works in 'the real world' and then apply it to your cartoon style. Are you practicing this by trying to draw realistic faces and bodies, or are you focusing directly on your cartoon style?
I've personally found that the latter doesn't work that well. In most cases, it's necessary to 'ditch' the cartoons and focus on emulating real life as closely as possible. You don't have to create massively detailed, shaded and colored portraits, but knowing what 'real people' look like and how to draw them opens a hundred doors for your cartoon style.
For example, focusing on real people will tell you that the bridge of the nose and the forehead of the top right character don't work out so well because the eye is placed too high in the skull. The jaw also needs to extend further back and we're seeing an almost front-view on the mouth while you're aiming for a straight side-view in general. These contradictions throw off the eye quite a bit. Cartoons allow leeway, but your foundation is wrong, therefore the stylized approach is not based on reality and it will look odd to us.
It's definitely possible to improve and learn by focusing on your current style, but it comes with the inevitable realization that instead of a hundred doors, only a couple will open on this path instead.
If you're up for it, I strongly recommend making use of our drawing tools and focusing on face studies and body gestures. Try your best to draw <em>what you see</em>, not what you <em>think you see</em>. When we draw 'from memory' without copying what's in front of us, we inevitably get details wrong and don't learn much.
This page has a good explanation of what I mean. <strong>Please be mindful, the post I'm linking to contains a lot of swearing!</strong>
http://imgur.com/gallery/0O7P8gu
I hope this helps, please let me know if I interpreted anything wrong or if you need more information. :)