[Carlos Silva] "a) So, would Vegas (studio 11) able to do this kind of animation? Could I call it “stop motion”? "
You would really need Vegas Pro for this because there is a lot of Masking going on in that video and Movie Studio doesn't have a Mask tool. :( So some of it could be done but not all of it.
[Carlos Silva] "b) Does plugins/software as "StepTime (Pixelan)" or “ScenalyzerLIVE” offer any additional improvement to Vegas to make this kind of creation easier? "
I don't think stop motion is the solution. This is straight animation of images which is best done with Track Motion in Movie Studio.
[Carlos Silva] "c) To create the images I thought to use the software Inkscape (it is similar to Corel Draw). What would be the best export image format (file type) to use in Vegas?"
I would save them as PNG with Transparency. There are a lot of transparent overlays in that video.
~jr
http://www.johnrofrano.com
http://www.vasst.com 
