Congrats on the Brewhemoth. Great fermenters.
Regarding depressurizing yeast, as long as you're capturing your yeast to repitch at around the 5psi mark, there should be no issues. I definitely wouldn't catch the remaining yeast after your higher carbing pressure.
I was going to go the same route as you for filling my kegs, but I ended up going with something else. I've basically put a corny liquid fitting on the racking port, and a corny gas fitting on the 1" port on the top.
Here are the parts:
-1" TC fitting with 1/4"female NPT:
-1/4" corny plug adapter:
-Corny liquid and gas fittings, with poppets:
The above is a little more $, but very convenient. just use a corny liquid\liquid fitting transfer hose from the fermenter to the keg.
The corny gas fitting is clamped to the top 1" port, and a gas\liquid transfer hose attaches it to a corny keg for potential blow off material.
The other fitting on the corny catch keg goes to an inline CO2 regulator which I use to bleed off excess pressure, just like a spunding valve, only much more precice.
So with the gas port on the top, I can pressurise the fermenter either from that port, or from the port on the corny catch keg.
I'm still on the fense about dry hopping in the fermenter, but until I figure something out, I'll continue to use finings and dry hop in my serving keg. I add gelatin, and a hop bag into my serving keg, fill the keg, let it set for 24-48 hours, then pour off the first beer or so to get the gelatin out, and you have clear beer.
Now for fruit beers, I would suggest making a fruit puree, adding it to an empty keg, purge with co2, pump up to a couple of PSI more than your fermenter, then attach the liquid port to the liquid port of the fermenter (with parts suggested above), and the positive pressure will serve the pureed fruit into your fermenter. Done. A little bit of extra cleaning, but hey, it's all under pressure and naturally carbonated.
your parts list looks pretty good...I would suggest getting 10 1" clamps with gaskets, and another 5-10 gaskets.
hope that helps.