Hey, its great to see all this in print!! Although I am by no means an expert, here's how they had me doing it in Takamiyagi - Sensei's dojo last time I was there (almost 2 years ago, though I'm headed back in May)
Defender always starts in L sanchin, attacker always in L except for #3,5,9,10 (which start in R sanchin) I didn't check this part of your post very closely, but it looked right to me...
#2: defender steps back into a medium-level horse stance for the final shoken blow, which is often demonstrated as a seiken for safety.
#4: Attacker does a left side snap kick instead of a front kick.
#5: Defender maintains L sanchin throughout, using slide steps as spacing requires.
#6: The defender's second palm-heel block is directed somewhat downward to clear the face/neck for the finel return strike.
#10: The defender steps into the attacker with a medium-to-high horse stance for the elbow/back fist, then continues the movement for the throw. This movement would be nearly simultaneous, except for safety and control issues, and the upper part of the throw is directed towards the clavicle and/or shoulder ball-joint for a break/dislocation during the throw - but NOT in the dojo!!
If I see anything different on this trip to Okinawa, I will post it directly. Hope this helps, and wish I could train with you guys - all I have to work with is the students I trained, and they obviously do what I do(for better or worse!!). Take care