Man this list deserves more posts. Its that awesome. Just a few minor nit-picking details: (Sorry!)
1. Two sentinels are going to die, especially since maybe one will be on the table to start with. My personal viewpoint is that if you are going to take tanks, especially AV10 open-topped walkers, you need multiples to force your opponent to disperse his AT fire. I'd recommend a Chimera with Improved Comms one of the vet squads maybe? And throw in a Demolisher for close support and another 2-3 sentinels maybe in separate squads for more Deep Strike goodness. One of my favorite things to do is charge things with my sents- No one expects it, and while it won't kill much, it'll take a while for something to kill it. Unless you are Grey Knights.

This is not taking away from the Droptroops fluff IMO because you need something to secure the area, as you said.
2. I really like the addition of an INQ with a few mystics, that should give you complete control over the Deep Strike rule in your games.
3. The culexus assasin is an interesting choice. I think the souless ability is going to win you games when used correctly. Even Orks and Guardsmen and Tau etc suffer from being too close to the bastard as normally everyone takes Ld upgrades. And why wouldn't you use him correctly?
4. I also Really like the concept for your squad damocles. My idea for something like that included three meltas. IMO the third melta kills infantry well enough to be worth packing for the added AT work.
Lemme know if this helps Stitch! And/Or Poke holes in my plans!
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