Seivarden might be biologically male, but the Radch culture seems set-up language- and reproductive-wise so that one doesn't really have to identify one way or another if they don't wish to. So she could think of herself as male, female, genderfluid for all we know since we don't have access to her POV. Likewise AM is probably agender or doesn't care much for identifying in the first place (like Breq who still thinks of herself as "ship".)

I think Ancillary Sword pretty much spells out what would happen if Breq's ancillary implants were ever removed; the entity Breq would be destroyed but the host still wouldn't come back. Instead a whole new being with both Breq's and the original's memories and personality traits would be "born".