Small note on using TAB to target.
Tab will not target mods of the same faction as you.
IE if you are Omni pressing tab will not target Omni sided mods.
I've check this alot and it is true (for me at the very least) in all mission types.
Small note on Hidden Rooms and loot
Not as sure on this one but it seems a Hidden Room has the same random chance of having a chest/box/trash/crashed android/etc as any other room. I've also never notice the loot being any better than normal when I do find them.