don't know those answers, but i have found a good way to teach basic skiing, just a little fwiw.
i taught two kids and ye ol' lady this way. pizza pie french fry? nope. side slip down a suitable grade. the kids were first and i made them repeatedly side slip/stop (both sides) a little knoll on Gore's jamboree trail. then when they git that i made them seasaw down. it wasn't long till they could use their edges properly and with confidence. the problem with snow plow is it's weak and they use both inside edges. then when it comes time for real turns using one inside and one outside edge it gives them trouble and a lack of control/confidence and the newbies worst fear - I CAN'T STOP! side slippin teachs them to stop, use correct edges and gives them balance/confidence so they can shove the skis out there to turn or stop. from there it's easy to move on.
when it was the ol' lady's turn she took several lessons last year and got nowhere and was frustrated and scared. so this year i said enough of this crap. you side slip down this hill and you keep doing it till you can do it good and are confident. bingo. now she's capable and confident AND having fun!!! the grade has to be steep enough to slid on.
don't know if you could get paying customers to do this. most just wanna start skiing down the hill. also, practicing side steppin up the hill tires them out very quickly, it sucks to do and is not near as good as sliding down for advancing their skills.
it worked really great for us. fwiw.