I have a question about restoring damage from PDS fire with Duranium Armor tech. Let's say I fly into a system with several Dreadnoughts, one of which gets a hit from defending PDS and I use sustain damage to cancel it. Technically, PDS takes place before the first round of combat, so am I correct in assuming that after that round ends I could repair the dreadnought damaged by PDS?
You are correct. Since that unit did not sustain damage during that round of combat, it is eligible to repair.