That's the ticket!
I knit a booga using Wool of the Andes from Knitpicks. Alot of folks have used a solid, less expensive yarn for the base and a little ways up the sides so they can double the Noro and use it only on the parts that make the most difference.
I think it will be important to double the yarn, otherwise, you are going to end up with a not-so-sturdy bag.
The washing time depends on so many things....whenever you are felting, you just have to check it every 5-10 minutes.