If colony/outpost capture will be in game, how will the production work in such a case? Will captured shipyards gain immediate access to the player's current blueprints but not those of the previous faction? Do non-player factions even use blueprints in the first place, or is it simply by faction 'ships' they have access to?
Other factions use blueprints, and ship production is based on the faction controlling the market. There'll probably be a bit of nuance as far as, say, "independent fleet spawning at other-faction market"; still working through some of these.
Will we be able to stack stuff like corrupted nanoforges to get better quality ships or will it be one per type or one item total?
You can only install one, yeah.
One thing you could do would be to have a ship production center that would stock ships to a certain level and then pay shipping costs to bring the ship there. The “shipping” would be what was “rushed” rather than the production.
This would also have the side effect of making long resupply points potentially less efficient than short ones.
Yeah, makes sense, but that much detail is too fiddly for my liking, if that makes sense. I'd sooner just have a rush order insta-produce things, no questions asked - at least that's simple and doesn't add hard-to-convey/learn/interpret behind-the-scenes mechanics...
My biggest concern with a self-managed stockpile would be making sure I actually have the right things stocked; in a large fleet there can be lot of hulls and armaments to keep track of. Being able to order a variant instead of a hull and a list of weapons could help a ton, and would be quite convenient in general. Being able to order weapons to be built from the refit screen could be helpful as well.
While you can't order a variant, the hulls you produce do come equipped with something; it picks a random variant and then autofits with what's available. The idea is to reduce the amount of hassle if you just want to bulk up your fleet and don't particularly care about the specifics.
In the context of degraded engines engines specifically, sneaking up isn't usually a practicable strategy. Although I've never had much luck with that strategy anyway, the few times I've tried... Don't get many opportunities to practice it, though, because it's almost never viable for me - either I'm in/around a colonized system, hunting bounty targets, in which case I can't turn off my transponder without *** off allies, or I'm exploring the outer systems and the supply cost of e-burning is too risky.
Yeah, fair enough. In vanilla, anyway, it's mostly applicable if you're trying to deal with a named bounty that won't fight, or if you're sitting in ambush somewhere. The "E-burn costs no CR" skill effect is a big consideration here, too. Though if you're trying to engage a stationary target, a Sustained Burn can do the job too.