Yes, we have mounting holes for both pcb- and plate-mount stabilizers for 2u spacebars.
Although we have no tenting angle on the Zplit, there will be holes for mounting tenting legs on the bottom of the case.
Yes, you can find case files as well as layout references on the resources page.
Only one encoder can be added on the Zplit on the top right corner of the right side.
A build guide will be released before Zplit starts shipping.