I assume both of these are horizontal shocked versions with the earlier style frame.
* Yes, at least mine is.
My list of things on the build would also include rear suspension work if not done within the last year.
* Rear shock has not been serviced (or ridden according to the seller) in a year, so at a minimum a servicing is in order. Not knowing the history, I would have this done anyway. I've read about some of the limitations of the original shock and may replace down the road, but my F/S experience is limited, and F/S tandeming is non-existant, so in the beginning I'm sure it will be sufficient for now. I also think I've come across some of your suspension threads on other forums and I don't have anywhere near that expertise or F/S tandeming feel.
Shifter wise, and component wise, if you plan to get dirty, SRAM 1:1 stuff is a known performer. Can be found at various levels and if you don't need a full rack of cassette rings is reasonably cost effective.
* I have no experience with SRAM componentry, I'll have to hit the LBS and check out a SRAM spec'ed bike to get a feel for it.
For serious dirt use, it seems every topic started ends with two choices let seem to always get you home. Kings or DT's. There may be more now, but few of us sway from what handles the torque and gets us home.
* The more I read, the more I'm leaning towards the Kings. Haven't read up on the DTs yet.
Stoker bars...it really just depends. Captains bars with bar ends...off road I don't for fear of one slipping.
* Probably an area I'll have to experiment with, and due to my captain situation will have to be flexible.
Thomson posts and captain stem, known perfromer. Stoker stem, old Cannondale or whatever Alex has that fits. Ebay may or may not have something, but the lengths often seem wacked.
* I have a variety of stems in the parts bin, and will probably depend a bit on final front end geometry.
Cranks, choices are small and you listed the ones to get new and have quality. Used...I like Race Face ISIS for our stuff.
* Never personally been a fan of ISIS, even I've blown up a couple BBs.
All the best with it.
Thanks PK