Finding the right software seems to me is probably one of the most important aspects of this project. After all it is a tool that will be used day in and day out to produce the cartoon. Most likely there will be several types of software. One for animation, maybe one for audio [if not included with the animation software] Then there is video editing software, maybe special effects software. Perhaps even some software to keep me organized, as you do not want to spend a week animating something only to realize at the end that you animated yourself into a corner and the week was wasted.
I like the idea of using open source or free software. However, I worry that they may not have the features I need, or may be hard to learn with little documentation.
I am leaning toward 2d animation, as 3d seems like it would be harder to learn. I understand the concept of 2d animation better as it is what I have watched most my life. I still remember when I first saw Toy story, how I stood in awe of what I was seeing. Being able to reproduce that effect would be awesome, but I have also seen homemade 3d animation and the medium seems to be less forgiving than 2d.
Ktoon, synfig and pencil are 3 open source 2d programs. I will check these out and give my impressions of them soon.