I don't work in JBoss, but I believe I have an understanding of some of your questions. JBoss will make seam work on all Java EE 6 containers, otherwize they would shoot them selves in the leg. It will be based on JEE 6 and it will come a Seam 2.x to Seam 3 migration guide.
Estimates, I believe medio september. My guesstimate is when Java EE 6 will be, then shortly or immediatly after Seam 3 and WebBeans will be out.