Little bit of nitpick:

It's okay that everyone knows an Inquisitor is on the planet some way or another (word gets around and all that), but I'd like if his shuttle and actual starship remain hidden for now. This is a request, and if you can figure out a suitably cool way to discover their whereabouts it will probably be okay.

And no, Terminator armor is not limited to SMs in the 40k canon. Inquisitors and at least one Witch Hunter that I can recall have access to it as well, albeit in a lesser form. Sisters of Battle probably have some as well, although I can't confirm that.