Planning the route for electric wires in a attic finishing project

dijastrow

I am in NC and finishing off my own attic. I have installed collar ties to affix the drywall to for the finished ceiling. The collar ties do not run all the way to the knee walls leaving me with a partial sloped ceiling. The attic is being divided up into a bedroom on one side and an open loft on the other. I will install a sub panel in the bedroom closet. The sub panel will be directly below the collar ties. Is it up to code to just run the cable up and over the top of the collar ties to feed the open loft on the other side of the attic? I do not want to bore through the collar ties if I do not have to. If I do run the wire above the collar ties do I require it to be in conduit or can I just staple it down to the top of the ties? Does anyone know what the exceptions are for headroom height for a sub panel. I want to mount it in a mechanical closet on an 8' wall. The unfortunate part of this closet is the height quickly drops off as it backs up to the sloped ceiling. I will have my 3' but not all 3' have 6.5' of height clearance. Is this going to fail the inspection?