Mouse infestation cleanup advice
This is really a subjective question, as every person has a different tolerance for risk and "ickyness". Mice can carry bacteria that cause respiratory ailments, and the notion of feces in one's home is unpleasant. 

Personally, I'd vaccuum all hard surfaces with a HEPA filter installed and call it a day. The bits in the attic insulation are there to stay unless you were to completely replace it, and that's a fool's errand, in my opinion. It's likely that there will be more at some point anyway, and if anyone is in the attic they should be wearing respiration protection. 

Good luck.