I can at least answer the 2 first questions.
1. I've seen 2 diffrent versions, #1 is a 6.5x.300 WSM
(Same thing as a 6.5x.270WSM) and #2 is a 6.5x7mm WSM they are two diffrent cartridges because of the diffrences in the parent cases shoulder placement.
(I guess I've seen Improved versions with 40 degree shoulders as well, I forgot about those.)
2. Yes Bushing dies will work for this application, but you could possibly need either the 7WSM or the .270WSM depending on the version you choose. It would be a good way to get the best dies for this cartridge.