14 gauge stranded is probably more common for the buss spine.
yes, you can use suitcase connectors to attach 18g stranded stringers to that spine.
yes, the prewired lionel leads can be used
For our ever changing temporary and holiday layouts, I bundled 5 strands of 14 g together (each a diff color). with some velcro cinches. I then run 18 g stringers w suitcase connectors as needed. Each year, I try to reuse the existing ones and add new ones as needed to reach new accessories, etc.
