It depends on each individual patient's case -- for example if the Dr is trying to level the gum levels and bond chipped / worn teeth at the finish of orthodontic treatment the lateral incisor could be 2mm higher than the central (and then bonded to the proper length) so it matches the lateral incisor on the other side. I tend to place the laterals about 1/2mm higher than the centrals but again this is dependent on each individuals treatment plan.

Yes. There are step bends plier that are larger than 1mm. If you wanted say a 2mm step bend another trick is to put two 1mm step bends close together on either side of the target tooth thus giving you a total of a 2 mm step. Having said all this if do in fact need a step bend larger than 1mm I typically recommend bracket repositioning.

Must be steel for the reasons described in the video. An advantage of using 018SS as opposed to a rectangular archwire is you do not add in undesired torque to the AW.

So long as it is Stainless Steel NOT Niti.