1) I haven't got USB2, how fast is transfer via ethernet compared to USB and USB2

The ethernet transfer is a lot slower than you would expect. It's faster than USB1, but it's a lot slower than USB2. If I had 20 gigs of tunes to load all at once, I wouldn't do it via ethernet. Ethernet is great for playlist management (especially since Jemplode allows hierarchical playlists) and for loading a few albums at a time. But for the initial "fill the player up" tune squirt, USB2 is the only way to go. Definitely get yourself a USB2 card (they're not expensive).