Lungeing, Longeing, Loungeing

Since I've been lungeing Starbuck on a regular basis to try to teach her the voice commands "Paso" (walk) "Trote" (trot) and "Galope" (canter) but I don't have a whole lot of experience on the line, I got the US Pony Club's Guide to Longeing and Ground Training.  Even though it's basically written for kids and has a lot more "safety" guidelines than most books on training, I'm finding it really useful.  Some things I've learned so far are:

• There is a special type of bridle called a cavesson which should be used when longeing.  
• Before starting to longe, it's best to teach the horse parallel leading (at 6-10 feet), then parallel longeing (where the person walks a smaller inner circle about 10-15 feet away from the horse) and finally "normal" longeing (where the person stays in one spot in the center of the circle).
• Horses shouldn't be cantered on the longe line until they're very good at walking and trotting, since it's more difficult for them to keep their balance in a canter.

I think I'm going to get a cavesson, until now I've been longeing with a string halter (Parelli style), but am thrilled to know that there are special halters which can give better control while being gentler on the horse.  This way I can also introduce her to the bit without pulling on it too much when longeing, since the line attaches to the noseband instead of to the bit itself.  Here's a picture of the one I'm considering: