Typically mosquitoes are not going to harbor in the lawn where the Bayer granules were placed. They are usually found in bushes and dense foliage areas. You can safely spray all bushes/hedges/ground covers and any areas you feel mosquitoes may be present on a monthly basis with Bifen I/T.
Yes, Bifen IT is an excellent option for boxelder bugs. Be sure to spray around the perimeter of the home, around windows, doors, etc. where the bugs could get indoors. You should treat once a month until the first frost. This product can also be used indoors around the perimeter of your home. The mixing ratio is 1 fl. oz. per gallon of water.
Bifen IT should only be applied to interior cracks and crevices quarterly (where floor meets the wall) and monthly to listed exterior areas as directed.
Bifen IT would not be recommended for fleas inside and cannot be used on carpets. It is only for cracks and crevices when used inside. We would recommend our Indoor Flea Kit.
There is a great video on how to use the kit here.