Getting the compass working is as simple as running the Compass test on CSD tool. This should be in the build info or somewhere.
The CSD tool also covers GPS, where there’s info on “Assisted position”, as well as the stuff in GPSinfo. Assisted position looks like what you might have seen on map applications before you get a lock. It can use either cell tower or wifi triangulation (not sure which or both). It also can use this in Airplane mode, suggesting it’s stored. [All this is with SUPL transport disabled].
Got suplpatcher working (gps.conf mis-edited). Indoor lock in 9s. 
Previously, it was taking 10 mins, losing it quickly and taking another 2 mins to get another lock.
Now, with the Google assisted lock, it won’t take longer than a few seconds (indoors), even with data and wifi disabled. The latter isn’t unexpected, but then why was it having so much trouble holding a lock without suplpatcher?
Whilst I swear GPSinfo deactivation and rebooting used to wipe GPS data, this no longer seems to be the case. Or rather, “GPSinfo deactivation” seems to delay lock a few seconds, at least in 4.4. It does not wipe last position nor the ‘awareness’ of 40 satellites. Rebooting likewise.
4.5 of HWG seems better but not really tested yet.