Alright! keep us posted on what your building!
I have never liked friction drive myself, don't like the look, don't like the weight up high and don't like the premature tire wear. Now, that's only my opinion for my riding style and my area. I'm sure there are many who love them and that's great too!
I like the look of the new Cranbrook wheels. They look tougher than the old style rims and I think they will hold up fine. As for the rag joint, I have no problem with them. I use them on all my builds and have never had a problem with any. Some were a real pain to get set up right, grinding down the rubber or making thicker ones, grinding out the center to fit the coaster brake wheels...but once I have them where I want they are rock solid.
As far as mounting a H.T. to one, the front mount was all that I made. I used a drop plate and U bolt. I brazed a strip inside the U bold so it wouldn't dimple the frame when tightened. other than that it was a simple mount up. I rode it for a full summer and I'm sure the collage kids were not easy on it. I haven't seen it since she bought it ( well, her dad bought) but I'm sure if there had been any problem I would have been the first one daddy would have called!!
And last, the tensioner....All the horror stories...I was worried about them as well. I don't like drilling holes anywhere in a frame but once set and tested I pinned mine so they cannot rotate into the wheel. I figured the cheep looking plastic wheel wouldn't last and have skateboard wheels ready to modify to replace them but I have never had a failure yet and my Spaceliner and Rollfast both have well over 1000 miles on each!
I think if you take your time, think out each step, do it right and ride it for what it is you will have a "Happy Time!" Remember, motor assisted bicycle, NOT motorcycle. WOW, that was allot of typing......I hate typing......