Adding an extra fuse block

[zoom45]

I'm going to add an extra fuse block in my left side cover. There's plenty of room for it but it's kind of tight to run extra wires through and around the box. This will keep from having a bird nest of wires at the battery and fuses scattered around the bike. The block I have holds 6 fuses. Right now my accessory wiring is:

Stebil horn used with a relay (mounted near the ignition switch)
Accessory plug (mounted at the windshield)
Trailer wiring kit
Driving lights with a relay

Do I run the power wire directly from the battery to the block or should it have a fuse in-line there too? What gauge wire should this be?

What would be the correct size fuse for each of the above accessories?

Thanks,
Zoom45