Hey Ian.

1. Yes, it’s not possible to upload multiple files for the main pictures. The main reason is that it’s not possible to reorder these pictures. Both features could be a good addition.
2. It’s weird for 2 reasons. First – it should be possible to upload just 5 pictures, second – I tried it several times and worked well. It was probably just some kind of Javascript fail.
3. I think that it was the same reason as in the #2.

Did #2 or #3 happen to you more than once?

-- Michal, http://WoodworkingWeb.com