Holy cow, fantastic contribution! Thanks a lot for this. It has saved me such a headache. I'd like to help with this if I can, but I'm a bit of a n00b (doesn't mean I'm not going to try though).

I'm curious - I know further up this was touched on briefly, but how can I add fields to the import? I'd like to add a field for product options, like skus and weights and so forth. Also some fields that would be helpful for downloadable products. Where can I learn to do this? Thanks.