Can I use Duty officers that I buy for dilithium or EDCs for missions where there is an exchange of duty officers? I have been using Doffs that I can get back with ease for missions where I exchange them for another Doff but the two times I tried no Doff was returned. Not sure if I needed a Critical success or what. The mission descriptions should include what kind of success needed for attaining the Doff. Is there anywhere to go to get a list of Doff missions and their rewards and requirements? I also think that the repeatable chains should have a listing how many times you done them and what rewards you have already gotten from them.
I'm not sure what you're referring to here, exactly. The Gamma Officer Exchanges (Bajor, Cardassia, etc.) will take any officer you can throw at them, with the exception of replicated holograms. If you're referring to the "Doff Grinder" missions at the academy, the ones where you slot 5 of one quality in to get 1 of the next-higher quality, than you can use any Doffs except the replicated holograms or the tier reward ones sold at the academies by Lt. Ferra / Stass.
Other than prisoner exchanges, I can't think of any mission that is supposed to exchange doffs that isn't guaranteed to at least give you something back. There are a few "grinder" ones that consume them to give you dilithium, but that's not really an exchange. If it is one of the Exchange missions that's not giving you a Doff back like its supposed to, I'd suggest filing a bug report.
Heretic also stated that you can't use doffs that were part of C-Store bundles (e.g. the Deep Space 9 Bundle, not the Doff Cadres or Packs) in the Academy reassignment grinders because you can infinitely re-claim them from the C-Store.
I am referring to missions like "Instigate Defection" the ones where you leave a diplomat at a consul for the exchange of another. Thing is if you need a Crit to get a Doff the mission should state it. Also they need to add to the assignment chain gui to let me know what rewards I have collected and what rewards if any are left to collect, like if you need a crit for a specific Doff like in the nebula(Rolar, Iridian, etc) Doff missions. I have 3 toons I play with and it is getting very hard to keep up with who completed what and got what reward.
I am referring to missions like "Instigate Defection" the ones where you leave a diplomat at a consul for the exchange of another.
What you describe sounds like the Officer Exchange Program, not Instigate Defection (you don't lose any doffs for that).
The Officer Exchange Program is a repeatable assignment unlocked by completing the Consular Authority chains. There are variants for 7 different species (e.g. "Bajoran Officer Exchange Program" is unlocked by completing the "Consular Authority: Bajor" chain). The last assignment of the chain, "Station Provincial Administrator," consumes a doff but does not reward one; only the repeatable "Officer Exchange Program" is actually an "exchange".