DON - I sharpen my blades same way as Kraig, with the 4-1/2" angle grinder. I think I end up removing less material from the blade which means it should last longer.
I gave up on the hard coated blades, they cost so much more and I sometimes hit some pieces of crushed rock along the road and they nick/chip pretty easy.
Most of your cutting will be done with the outer most half inch of the blade depending on your mowing speed so most of the wear will be there. Like Ken says, don't round off the corner, that's what causes the strips to not be mowed when turning corners.
I wire brush all the accumulated grass & rust off the blades, sharpen, and like Ken says, don't get the edge "Blue", all from the beveled top edge, and if there's any burr, make a light pass down the bottom. And after the blade is sharp I balance over a small round screwdriver shaft, and the center hole must be split by the shaft. If there's a small nick I just leave it, if it's big I may try to get a bit of an edge to it, depends on where it's at on the blade. If it's toward the end I'll try to sharpen it but if it's in an inch or so I leave it.
I probably get blades too sharp, and too shallow of an angle, they won't cut skin unless you really try, but will cut soft wood. I normally sharpen the blades on my 38" deck every 3-4 mowings of my 2+ acre lawn. I think the sharper blades pull easier, and don't hurt the grass as much.
LARRY - re: broken zerk, yes they press in, you need to remove the spindle from your frt axle, using a small punch, knock the broken end into the spindle bore, replace the spindle, and with light taps from a small hammer tap in the new zerk Charlie posted pic's of. There's a "Special tool" for that job actually, but you can get by without it if your careful.