If you need to keep everything as part of the same gang list, then I'd recommend the venators, they have access to a wide variety of profiles, skills and wargear -- perfect for making an non-typical gang like this. Venator gangers can be pretty much armed and armoured with anything from the get-go, and you can prioritize what skills you'd like your gang to be centered around, so it should be easy to represent your Inquisition killteam exactly how you'd like them.
As for the daemonhost, if your group isn't super strict about gang composition, the chaos cult witch could work well. Otherwise, you could run the Daemonhost as a brute to represent its unnatural strength and resilience or as a ganger with its wargear representing its powers. For example, a player in our group uses a handflamer and grapnel launcher to represent his psyker's powers.