It's possible to overheat and damage any pad. They all have limits. Unless you know the actual brand and model of pad it's tough to say what they can or can't handle. A semi-metallic street pad probably didn't need 10 60-5mph stops. Most street pads take 5 or 6 stops until they start to smell. If you saw smoke you might have gone too far and toasted them.
A fluid flush is never a bad idea. If it's old you might as well do it. If it's not a higher temp fluid you might as well do it. For DD you can get away with just about any DOT4 fluid from the autoparts store. If you want higher temp a can of ATE Superblue is not expensive and one can is usually enough to flush and bleed.