Soaking potatoes is a good move if you're going to fry them, to remove the surface starch. (BTW I don't know why this is good but I know for sure that it's good.) also, you should fry them twice, for sure, but again I'm not sure why: read Julia Child. If you cut your potatoes in advance you can keep them from browning by keeping tham under water.
When I make mashed potatoes I usually just boil them unskinned, or perhaps just bake them. I never remove the skin--I like the rustic look, feel and taste.
Well anything else would amount to me telling ppl how to make mashed potatoes... Or be sure to read Julia Child on making fried potato pillows. You understand pillows you pretty much have mastered fried potatoes.
As far as mashed, just bake or boil them then let them sit unpeeled and they won't brown.