I could not agree more. Custom fields and an option to teach Autofill Magic is a very important feature. And it is something that we will implement. I know the 'autofill form' plugin, but I want to make something that is easier to use and manage. I imagine that you simply right click a field and chose 'Always fill this field with:' > then you chose among the predefined fields and your own custom values. Autofill magic is just two month old. Give us a little time and I am sure you wont be disappointed with the solution.
We have focused on web. 2.0 for a start, but the logic of Autofill Magic is universal. In the future you will see Autofill Magic supporting all the platforms you mention, bookmarking, press release sites, document sharing sites, video sites etc.
And yes you can use spun content in the article from folder option. Please see the
faq about the article format.