re: foot positioning - I don't feel there's a "right" way of doing things. Think Gee Atherton vs. Loic Bruni: completely different body positions, both have Stripes. I don't generally coach swapping lead foot or dropping the outside foot, not because they're "wrong", but because I generally find there are other things that improve traction without complicating things, and swapping feet is an added variable that gets extremely hard in tight, fast, and rough terrain.
No right or wrong, and I think it is useful to be able to do a little bit of everything so you're prepared when things don't go exactly to plan. We do switch foot pump track sessions relatively often for this reason.