There are a lot of things you can do to influence turn shape that do not involve steering after the skis hook up (which is different than the "stivot" a powerful pivot of the skis prior to their hooking up)-- (1) commit forward at turn initiation to bend the shovel of the ski to tighten the start of the turn; (2) finish slightly on your heels near the end of the turn to bend the tail of the ski to tighten the end of the turn; (3) vary the edge angle as required. The higher the edge angle, the tighter the turn. There was an extensive analysis of Ted Ligety's skiing here last year ("Hips Back for Hacks" IIRC) that showed how he uses a higher edge angle for a shorter duration than some other slalom skiers; and (4) add or subtract pressure by straightening or flexing the leg, which adds or reduces the bend of the ski (and thus tightens or loosens the turn.)
1. should it be considered a manuveur that happen before skis get hooked up?
2. should it be considered kind of steering?
3. before hook up it is easy to see that more edge angle results in tighter arc. but if skis already hooked up, i can only image that more edge angle would result in distributing more loading to inside skis only. it shouldnt tighten the arc further because the skis is traped in the glove.
4. is the same consideration as 3.