I only did this once and I don't remember having to disable alarms first but I'll definitely double check this and it'll be included in a video at some point.
So if this is where the ship's circling and attacks you when you leave? I've noticed the settlement is red after I removed the power regulator maybe and maybe there's no way to avoid that. But otherwise I'm unsure it's working as intended. The way ships and ground assets interact isn't very stable in my experience.
I do carry engineered shields and dirty drag drives on my Krait Mk2 just in case though.
I'm still actually unclear as to what disabling authority scans is but I am beginning to think it's got nothing to do with guard scans. I think it might even be to unlock all authority "elements" in the map, freeing you up to discard your cloned ID. I'm going to test this and it'll absolutely be included in the infiltration video because that would be an awesome feature if I got it right.
As for scavs, I've got you covered, mate. They're really difficult to handle if unexperienced but there will be a video or twenty on this. Quick basic tip right now though, if you can get a G2-G3 executioner and use stealth on the rooftops, you can kill the first one before they get their shields up in one shot. It'll alert other scavs but ignore them and go around (taking the long way round if you have to) to another side of the map and attack one that's still unaware. Then go
Disabling Authority Scans makes it so you can walk through any door regardless of your clearance level. It disables the scans doors automatically do to check for clearance level. After disabling, you'll notice doors no longer even show a clearance number on them.
However you still need the correct clearance to interact with other system panels like power shutoff or any other shutoff panel.
back and repeat. As I said in the video, they do reset (you can see one resetting in the video, I just left him alone for 30 seconds and 2 seconds after that clip cut to another scene, that scav was one-shot in the back).
So if you get swarmed? Run away, hide, wait, reset. The more you do it, the easier it gets. NIght vision obviously helps for the night time though but that's not readily available just yet.