1) Assuming it's based on the Zenith, I think you'll have lots of room, using purt near any size wire. That zipper coil I put in my Zenith has 6 strands of 28g and measures 9mm long (wide?)!
According to the advanced mode at Steam Engine, a dual 30g, 2mm ID, 1.5Ω setup takes 13 total wraps and...