I put a S-A front drum brake on my old Schwinn Cruiser and was dissapointed with its stopping power. Others I have talked with have expressed similar thoughts on these. Now the coaster in back works as well as good V-brake would but the back brake is always less effecive in stopping power.
My feeling is that the OP should be wearing out his front rim faster. Cleaning off the rims and brakes would likely add life but rim brakes will wear out rims, particularly in when the going gets gritty. Accept it and replace rims as items that wear, or go disks. A coaster for the rear is a good option with trade offs. You can't back pedal, bothersome at stops. Braking power is only optimal with pedals at the 3:00 and 9:00 clock position. Disk brakes are costlier and heavier.