#1
I'm not that far into the game, having recently completed the Horizon mission.  I purchased a pistol damage upgrade from the shop on the Citadel, went back to the tech labs to apply it, only for it to tell me that I needed one more.  Okay.  So I picked up another damage upgrade, this time from Jacob's loyalty mission, went back to the tech labs, and it STILL said I needed one more...

Something isn't right.  I checked the wikia, and it said the Sabot Jacketing upgrade is unlocked after collecting two damage upgrades.
#2
Probably has more to do with game play choices than any tech type matter, so ask in a spoiler / hints forum instead.