They are completely interchangeable and fit fine. I have not tried one of the new D2 carbon fiber lower shafts yet but since they fit D2 they should fit D1 also.
Yes. I am just going to stick with the WS6 Master and 9” coil. Manticore with 11” coil is simply deeper here in the iron mineralization I most often hunt in.
The same stuff is for sale in this forum’s classifieds.