AI Retrofit seems to only use the base skeleton crew needs of a standard ship when determining OP cost
yes. and it is unlikely for this to change anytime soon, although I would like it to. there is a way to do it, but my plate is full at the moment. same thing in regards to Automated Robotic Drone Factory.
I can't seem to use them for anything that would otherwise require marines
they should be good for anything in vanilla raiding. the fact they are not working is likely another mod overwriting 'Crew Replacer' and what it dose to the raid plugin to allow this to happen. try using the latest version of nexerelin, and if it still dose not work, Crew Replacer has a patch that should. if that still dose not work, ether the release version of my mod is bugged or there is a compatibility issue going on.
they do not work for the bar quests yet, and don't work for anything to do with nexerelin (like invasions, for example) yet.
combat robots do not gain XP. raiding can still give the humans XP though, but only if you have the humans with you.
Order of losses for drones vs humans
order of losses is kind of complicated, and the current version might have the priority set wrong. so here how it should work though:
first crew replacer gets the crew a job wants, so if it wants 45 crew to salvage something, and you have 300 'crew' and 40 'salvage robots',
it will look at the priority for both ('crew' = 10 and 'salvage robots' = 9) and try to get the 'required crew' in order of best priority to worst.
(so 40 'salvage robots' and 5 'crew')
if you had more 'salvage robots' then 'required crew', it would only call 'salvage robots'.
if 'crew' had a lower priority then 'savage robots', it would call 'crew' first, and because there is more 'crew' then 'required crew', it would call only 'crew'.
if 'crew' and 'salvage robots' had the same priority, it would try to get random 'crew' and 'salvage robots' using some math that acts like all the available crews were picking straws.
now how this relates to crew losses:
when calculating crew losses, the code looks at the crew used in a job example: (40 'salvage robots' and 5 'crew') then randomly try's to get crew losses using the 'drawing straws' math thing, using crew used in the job as who draws the straws. so in this case, it would be 8X more likely to loss a 'salvage robot' then a 'crew' (there is 8x more 'salvage robots' then 'crew'), but it would still be random, if that makes sense. so there is a change that you would lose all 5 'crew' anyways. or would lose only 'salvage robots', even if you were set to lose 40 crew.
both the loses and crew for job functions are also effected by something called power. think of it as a multiplier for how mush each unit is work in calculations. but 'salvage drones' and 'crew' have the same power, so it dose not matter here.
i hope that all helps, and I'm glad your enjoying my mod. I'm working on an update for it now, although its far from finished, it goes well.