Do you recommend that you always do the rotations you used in the seated alternating shoulder press and in the 6-direction fly, or were these the way you decided to do it for this workout. In particular, I thought keeping thumbs up was safest for side and front shoulder raises.
I prefer palms down on the lateral raises because it recruits more muscle fibers that way (from lateral and even posterior delts). Shoulder impingement can be increased by overhead shoulder usage as well as palm-down anterior raises, that is why I like thumbs up for the anterior raises. If you don't like my variations, of course swap as you see fit.
Do you get much triceps stress from the triceps moves where you were balancing on forearm? For me, this turn out to be mostly core moves as I have to back off the weight to keep balanced. I actually did not do the one where you move the weight in three directions while in one forearm plank as it looked risky for my old shoulders.
Since you are in plank, more emphasis gets placed on core and shoulder stability rather than triceps, I get that, but that is why I place the "heavy mover" exercises at the beginning of the workout. The "Robbins Rocker" where you move the weight in 3 directions is, and should be, done with very light weight. I have tested it and don't have any problems with it, although I can see some people having issues, which is fine. I still recommend you try it, even with just 2 directions (side arm extension and then triceps kickback) as extending the arm laterally has been shown to be an incredible core recruitment exercise.
The triceps are being worked on nearly every single chest and shoulder exercise in this workout, albeit just as synergists, but for just a 30 min workout, I would rather get more "bang for the buck" by doing chest and shoulder work rather than focusing solely on such a relatively small muscle group such as the triceps. That is why the triceps-only sets are sparse and often include other muscle recruitment.
Multi-joint movements not only recruit more muscle fibers and burn more calories, but they also improve neural adaptations better too!
For chest multi-set, I prefer to do the iso move (flies) first. The idea is to work the pecs, then use the triceps to work them so more with a DB press, then finish things off with a body weight move. Any thoughts?
Strength training always recommends large muscle groups with multi-joint recruitment first before "accessory" work. For example, a chest press has more muscle recruitment and 2 acting joints involved (shoulder and elbow). I would never have someone do a hamstring curl machine and then go do heavy squats because you are pre-fatiguing the hamstrings potentially leading to an imbalance in muscle recruitment for the heavier exercises that require more strength.
By doing iso flies first, although the elbows are isometrically involved, you are targeting the pecs only, so if you then progress to chest presses, you may over-compensate with other muscles such as anterior delta or triceps because the chest is already fatigued. Plus, rather than doing say, 30lbs for 8 reps of chest flys followed by 40lbs for 8 reps of the chest press, I would much rather do 60lbs for 8 reps of the chest presses followed by 30lbs for 8 reps of the flys.