Regarding the black outline: is this where the limbs overlap to create an elbow or knee, etc?
I believe I have fixed this in my animations in Spine by using a "patch" - which is a trick from the other animation tech stack I have in my game using Anime Studio 8. A tut here by the Anime Studio guys explains what patch layers are: http://youtu.be/vGNRSqWSeAI
Basically Anime Studio is a vector art plus animation tool which I had been using up until now for all my in game animations. I export the results to a sprite sheet. Unfortunately my game is character driven and due to an explosion of sprite sheets for the animations I'm basically having to move to Spine. I'm still going to use Anime Studio for cut scenes.
I've only played with the trial, but by creating an patch (50x50 png) which is the same color as the characters skin in gimp, and making a new slot on a bone to attach it to, I can position the patch over the part where the black lines over the arm & leg joints cause a problem. It has to be positioned correctly in the draw order, and scaled/rotated/moved to fit. Also it needs some tweaking as the joint moves, but it seems to work pretty well.
Once I get the full version I can see how it looks in the game, but it looks pretty good in the editor.