2) Is Jemplode the only way to upload animated logos?

Its the easiest way, but i'm sure someone could hack some other method. Keep in mind that you need the hijack kernel installed to do this. Jemplode has some cool features, you should check it out.

3) Is there anywhere that lists the additional features between 1.03 and 2.0?

I dont think so. Maybe in the faq? Reading the release notes gives a general idea. A official manual will be available when it reaches 2.0 final.

5) I wondered if its possible to have a random visualisation shown (say change every 30 seconds etc). I've searched the forum and all I've found is an old thread about v1.0 beta 10 and a wish list item. Did this ever get done? I see in config.ini there is something to do with favourate visualisations.

There are various options for changing visuals under the visuals menu. Change after every song, etc.