Re: My 20's Style Touring Build
re: wheel building. Lace it up like a conventional 36 hole 3 or 4 cross wheel. Remember to brace the spokes across each other at the broadest intersection, just like a good mountain bike wheel. Nothing fancy necessary or desireable for this application. With thicker spokes, you might find your task a little more difficult as you can not readily flex the spokes the same way. A cheap flathead stubby screwdriver that is filed narrow to fit in the spoke holes, will speed up your work.
re: clutch arm. Mine came with a little brass part that slides over the cable, with a securing screw to hold it. I am not sure about yours, but I bet you can make do with a conventional nut and bolt, esp if you hacksaw the bolt a little or drill through it for the cable.
Yes, you can put the wheel toward the inside of the frame. Make sure it is really secure and keep it tight, or it can rotate into the wheel, esp upon pedal starting. See my thread on motoredbikes.com Chain Tensioner Idler related accidents.
You can keep cable ends from fraying by soldering/tinning, by heat shrinking, by dabbing with JB weld, or in a pinch, Super Glue if the cable is new and perfectly clean. Also, old spoke nipples can be pinched on as cable ends.