Take a center punch and punch either side of the pin. Then take a drill bit the same size as the pin and drill down just below the surface to remove the head. Take a drift or pin punch and a BFH and smack the pin all the way out. Done.
Yep, and a stover lock nut or nylon lock nut. I like the stover ones better since gear lube might break down the nylon over time and soften it.
Bolts, especially hard bolts like to break because the the coupling will "work" on the splines . Not much, but enough to shear the hard bolts. The soft original pins work the best.
42merc is correct. The pins are very soft and will "give" a little if the splines are worn and move around some--hard bolt will shear.