#1). Obviously, mecnhanically. Sand it off. Buff it off. Grind it off.
#2). As I recall the Am Rifleman article, this was a "porous" finish calculated to hold oils in the pores to prevent oxygen/water contact that causes rust. I think that many "blue removers" will tackle it, but I would ask Brownells [brownells.com] about their products. If you have to be crude, "muretic acid" is available at the hardware store (hydrochloric acid) should do it, but hard to control. luck