This was discussed recently as well. I can't find the thread but I think I can summarize some of trackhead, et al, advice:
1. Make the transition slow. You will be using de-trained muscles in your foot and experiencing a range of motion much more taxing than normal. You'll be sore.
2. Make the transition with some barefoot running on grass or another soft surface. I don't think this has to be long but it should be form-specific so you can retrain yourself.
3. Attempt to strike on your forefoot and not your heel--make this an active process. I don't know exactly how this is done but I'm trying this; some part of this process seems to be a shortening of stride and landing underneath the body. A few people have mentioned using the Pose method but all the literature I've seen on this is for-pay only. Obviously a high-heeled shoe induces heel-strike so some form modification will be necessary.
4. Your foot is designed to correct your pronation to some extent. Some of this will be corrected by a stronger foot and some may need to be corrected by a change in form. Concerning the leg length--well I don't know anything about this.
I'm trying to learn this as well and I don't know all about minimalist shoes, etc. Certainly trackhead or someone else more knowledgeable can answer your questions more appropriately but they seem to be on vacation. I was quite skeptical about all of this but it makes very good sense. I already cycled shoes (about 4-5 brands/styles I run in on a regular basis) so I get some variation in foot stresses but trying to run in flats with a forefoot strike is a little different.