Pirate Massacres, BGS and what is going on

I am a new player (3-4 weeks) and have been learning quickly and enjoying combat over everything else. I am playing with a friend and have been stacking pirate massacre wing missions in an anarchy island, however what I can't find out is how BGS and pirate faction influence levels might be affecting the availability of massacre missions from our source factions, as this has changed massively recently.

We have found that a recent war (probably triggered by us taking max rep/influence rewards for a lot of things all at once) in one of the source systems caused missions to dry up completely. That was fine, we took off and unlocked engineering and pimped our Vultures. However, now we are back, the war is over and we are still seeing a huge change in mission offerings from factions, even after rolling the board over the course of a day or two, and I am wondering what else is understood about this as I haven't been able to find specific answers with my google-fu.

To pre-empt some suggestions: we are both allied with everyone, the pirate faction is an isolated island so no massacre missions to other pirate factions in other systems, I know missions can change every 15min or so.

Does the pirate faction influence level in their system impact the chance of nearby 'good' factions offering massacres? Our target has been told to sit down so hard by me and my friend that they have lost control of their system and are at 1.5% influence. If it wasn't their home they would have left.

Does the system flipping from Anarchy to Low Sec mean the other nearby minor factions are no longer particularly bothered by the pirates? This would make sense but if that is the case then I have another question:

How can we repeatedly squish hundreds of pirate ships from one faction without them becoming irrelevant to their neighbours? Or is it just a case of having a few pockets set up at allied and switching between them as factions decline. If that is the case – what would make the local pirate faction regain influence without player assistance? Does this just increase gradually to the point where they can contest the system themselves or does nothing change unless players do things – in which case these pockets are going to be 'ruined'?