i'm pretty sure your safe, your reef is one of the best stores around.
Most stores do highly medicate their fish-only side to decrease fish loss. I'd be doing big water changes.
I would't say "most" but the good ones do use Copper. I have seen too many fish with Ich to say "most stores"
The best way to acclimate is a drip line. I don't float bags anymore as there is no telling what might get into your tank if a hole get's poked in the bag. I keep the bucket witht he fish in the stand so the temp stays warm as well.