1. cold, probably wet at points and getting slightly warmer further south. You might get lucky and be warm and dry all the way, but I tend to find the range of weather pretty much the same as the UK (certainly for France and N Spain).
2. can't remember it being a problem on the main routes.
3. passport, v5 (log book), insurance doc and drivers license. Try to make sure they all have the same name/address to make things easier. I think a photo license is going to make life easier too. Photocopies of these are a good idea. Talk to your insurance company, but they'll probably want you to specify dates and duration for Morocco (and France/Spain?). The Moroccan authorities probably won't care as long as they can check the 'has insurance doc' box, and you don't get into trouble.
You should go over to N Africa, it's not as difficult as you imagine.