I realise this might seem entirely noobish of me to ask, but seeing as how I'm new to MMO terminology and this is the place to ask....
If I equip and use the Scorpion Fighters item, is it strictly one use only and then it's gone?
50 uses. Each spawns a squadron of 3. You can only have 6 deployed at any one time. You can launch them if there's an enemy within 15 KM, but once they're deployed, they'll fly at whatever you target, regardless of distance. I once got them to chase down a Cube squadron from 50 km.
They have proven a most useful backup to me, so I flew the Vault mission again yesterday just to equip myself with another set.
Warning: you can't receive another 50 squadrons until you have completely used up the current 50. (And it's true that it's really only 49, because the 50th squadron doesn't actually spawn. This might be a bug.) Yesterday I completed the Vault and selected the Scorpions reward with one squadron of Scorpions remaining, and received an error message. So I flew another mission during which I used my final squadron from the original, and then mid-mission I hailed Starfleet and selected the Scorpions as a reward to complete the repeat of the Vault mission. I am happy to report that I know have another 50 uses of the Scorpions.