Agreed, great post Alberto. Very well thought out.
I'll also second Alberto's recommendation of Matt Cresci. He is a fantastic coach.
My new 99 will have a really nice and complete data system and I'm really looking forward to utilizing this with Matt in the ways that Alberto describes. However, even if you don't have a fancy data system, Matt is really effective with just the Solo2 and the GoPro. He helped take a second and a half off my lap times at Sonoma in a day or two.
Now I just need to finish the car! Man, this is a long process.