No, most people don't complete their yurts in the 10 days. The course covers all aspects of making the frame (and the steam bending equipment), but most of the yurt frame components need to remain in the formers for 3-5 weeks. If you make a small 12'-14' yurt with someone else you might just prepare all your wood but will need to return later to collect it before finishing and notting together. Everyone can finish their wheels and prepare 30-40% of the rest of their frames.
Yes of course, either at the next yurt course or come to one of the monthly steam days (£50/day or £25/half day) to collect and steam the next lot of wood prepared at home.

No it doesn't, but there is plenty of time for general questions about felts and canvas covers. If you want a fitted cover for your yurt frame I can give you a quote.
The costs are for the wood, string and oils (timber price list available upon request), depending on the size of your yurt and how much wood you buy from me this is usually in the region of £200.
People often come with friends or family members everyone is welcome, they'll have to pay for food, £100/person for the course. If they're taking part in the course and making the same yurt it's half the course cost on top as well ie £200.
Anything from 12'-18', I don't recommend going much bigger to start with.