i also have an nc (nc2) with a bose system.
the driver’s door base unit was blown when I got it.
i replaced with a second hand bose base unit in the end.
however, I did learn most of the answers to your questions while sorting it out!
ok, the Bose speakers are “wired differently” took me a while to work out what the hell this meant!
basically, the bose speaker and wiring loom have Bose connectors.
so if you want to put in non-bose speakers you have to cut the bose connector off of the loom and then wire normally.
I actually brought a set of aftermarket speakers to put in but because of confusion around bose being wired differently, I got the secondhand bose unit.
I still have the aftermarket speaks and I only want £20 for them but you will have to come and collect them if you want them.
here is the forum thread for them