Does the AI share the information across all instances of that spoiler?  IE, will any future Necrons in other systems know the details about the player's ships performance gleaned from the battles in Orpheus?

The AI shares information on a racial basis. So all Necrons will know the same information, but different swarm races won't share with each other.

There is mention of keeping the shields down to withhold that intel from the spoilers. Is that just RP, or are there behavior changes from them if they get that info? i.e. changing missile salvo densities and narrower targeting concentration.

The AI tracks information about your ships, including observed point defence performance and how much damage they took to kill in the past. They will include shield strength in that calculation when determining how many missiles to allocate to a given target.

However, in this case I was keeping shields down to deny them sensor information on the location of my ships. Active shields have a strong signature that can be tracked by EM sensors.

Great to see a new Steve campaign, and the new AI seems to make the Necrons a proper threat. I assume that they are similarly more difficult in their non-"advanced" traditional form, maybe even more so since they will be able to maintain their missile stockpiles. Very happy to see the AI learning better ways to deal with fighters and bombers, although I do wonder if they'll be able to handle more traditional bomber strikes from much longer range (40+ m km versus ~10-20 m km).

Hopefully as this campaign goes on we will see combat with a few different NPRs and most of the other spoilers as well. 

Steve, is there a setting to change the size of the spoiler ship classes? Or is it random and you've just had good luck here?

I'm curious how long you play a given campaign for, Steve. I find that long-lived Aurora 4X let's plays are few and far between, for better or worse, and that mostly because the nature of the game means that complexity and micromanagement ramps up quickly as the number of systems and colonies grows. I saw the screenshots of the galactic maps you posted in the Changes thread showing 100+ star systems in a single game. I don't know how you do it.

This is shaping up to be a very interesting campaign! Some very exciting new additions are noticeable, enemy trigger discipline against small targets and single fire control use in particular. And missiles with active sensors and retargeting? Don't believe I've ever seen that in the current version!

However, the Necrons had destroyed their ordnance stockpile once they knew defeat was inevitable.

Maybe they could stop doing that, now that we're finally getting a use for it beyond scrapping it all? Leaving their entire missile stockpile for us certainly wouldn't do, since it's seemingly limitless, but with an entire planet's worth of ordnance even the Necrons could miss a few dozen missiles here and there...

Five seconds later, a further four Furies were destroyed, although they were able to return fire from 37,500 km and inflict over fifty strength-1 hits on the Khopesh, including fourteen that penetrated its armour. The third volley from the Khopesh killed four more Furies, before it was buried under an avalanche of lascannon fire, suffering forty-five internal hits. The Necron fleet chose that moment, with the fighters at point-blank range, to launch sixty-one anti-ship torpedoes.

Did the enemy ships conserve their ammunition until they realized the danger presented by a swarm of fighters at point-blank range? If so, this is seriously impressive, but I have to confess I don't really understand this part, as the fighters' weapon capabilities should've been known to the Necrons from all the point defense fire they've observed.

Also, I can't help but ask, given your efforts to ambush the Thokt and the Thanatos group in the end, does the AI still have no concept of lost contacts/object permanence, or did it deem the inner system safe because a few months passed between the two fights? Really hoping for the latter, but very excited for the new update either way!