Yes, not having the hinge pillars welded to the rockers is good. That lets you work on getting them exactly correct.
I don't think you'd go wrong installing the doors to confirm or fix the dimensions in the cab. I know that would be a bit of a PITA, but you'd avoid the issues I had with my doors, having to grind the edges down for clearance in a few spots. It would be better in the long run to get the door openings where they should be.
I think I would leave the passenger side metal in place until the driver's side is done.
