My eleven cents answered to the best of my ability, without referencing anyone else's answers. Chase, I'm ditching this thread, so if you have any questions for me, shoot a PM. Hope it helps.
1) They would be Jump Infantry in addition to being Monstrous Creatures. Other examples in 40k include a Daemon Prince with Wings.
2)
"A Nemesis doomfist follows the rules for Dreadnought close combat weapons." (p. 54, GK codex) There's no prohibition on them being Dreadnought exclusive, and there are many other weapons in the game that function under the heading of Dreadnought Close Combat Weapon. (p. 74, 40k rule book.)
3) The person is overthinking the issue.
"Lord of Formosa: Inquisitorial Henchmen warbands are Troops choices in an army that includes Inquisitor Coteaz..." That's point-blank, couldn't be clearer. The second part of the rule,
"... and are not limited by the number of Inquisitors in your army." (p. 86, GK codex) Normally, Henchmen warbands are limited by the number of Inquisitors. Coteaz removes this restriction, and a GK player can have up to 6 warbands, limited by the FoC.
4) That was easy.
5) When Jump Infantry (type) take off or land in difficult terrain, they must take dangerous terrain tests. I see nothing that suggests otherwise.
6) Looks like they're referencing the Orbital Strike Relay on page 58. It's a Large Blast. If the psyker is under the Large Blast template, the psyker suffers Perils of the Warp.
7) Yeah, I bet they are having problems. Notice how Grey Knights don't have drop pods? That's one reason. Solution, drop pods should drop outside the zone.
The quote about Jokaero is pure fail. Taking 5 Jokaero guarantees "The Works" (6+) result. That's why it says 6+. (p. 50, GK codex)
9) Technically, that's awful. Even dogs know Lesser Daemons and Greater Daemons are Daemons, and it's not just a clever name. The Daemons Codex, which creates the official Daemon subtype, is newer than the CSM codex. I do not believe until now the distinction mattered.
10) The Turbo-Penetrator is a pure, unmodified 4d6, so I know in the case of the Monolith, the Living Metal special rule would not apply.
11) Terminator armour (p 63, GK codex) grants the Relentless (p 76, 40k rulebook), which allows a model to move, fire Heavy weapons and assault all in the same turn. The Lance Strike option on the Orbital Strike Relay is a Heavy 1 weapon, so yes, Terminators can move, shoot a Lance Strike and assault.