Nice. Were my tips pretty much in line? Did anything not apply? I ask so that we can have the thread updated with proper info for future thread searchers.
My situation was a bit unique, because I had the lower portion of the shaft already removed (refreshing the front end bits, lowered the front subframe). Looking at the lower shaft, it appeared to not be keyed, so when I was trying to reassemble it blindly, I assumed I had the wrong angle. In fact it was keyed, apparently, so doing it again I'd rotate it blindly until it properly lined up.
To insert the lower portion of the shaft, the gasket/bearing it passed through must be removed from the firewall. Note the orientation during removal, as it has to go back in the same way. The gasket has lips that must be sealed on both the sides of the firewall.
Other than that, attach the steering box side first (if disconnected)? Shaft can be removed from the steering wheel side with some gentle alternating prying. It just compresses in on itself, as you said. For reassembly, I gently tapped it back in place.
Every component of the steering system between the box and steering wheel is keyed in some way.