Most sectors (that we hear/read about, anyway) tend to be clustered around a great many other planets. Subsectors usually range around the 50-100 and sectors themselves number 200 or so.
This makes sense considering a sector that is largely alone will probably die alone.
You're right I meant to say sub
Also I would be hesitant to scale the crew up so high. Since I'd assume more space is filled with vast machinery. And the odd palaces and cathedrals hanging around even escort vessels.
I'm hardly scaling the crew beyond what is reasonable, even assuming that there are vast uninhabited (or deadly) sections of the ships the most sophisticated of systems will require manual maintenance. Ultimately I am guessing for a number of these figures based upon the closest figures I can find.
BFG describes the smaller escort ships for the space marines as being commanded
by a handful of space marines but crewed by an unspecified number of serfs and servitors which could literally mean damn near anything in terms of actual crew size.
Dark Heresy (or is it Rogue Trader? I always get them mixed up) gives crew amounts for various vessels. From small traders up to Luna class cruisers.
It would be Rogue Trader but as I haven't a copy of that (and don't know where to download one from) I'm admittedly having to guess on a lot of these figures.