Erwan, as usual, a huge and very meaningful post. I agree with everything you say for the most part (by agree I mean that I like your method of what you would do, since it is what you would do there really is no "agree").
I think that there is more room than you allow in your ideas for some products and companies exposure without being such a bad thing and at the same time allowing for some profit.
you can see that to date there is no "for profit" advertising anywhere on this site, the closest thing is a link to WWJ. There is also a link to Crossfit, I have done this without them even asking because I believe it is a good thing that helps people.
One concept I think you are missing slightly is that to get the "better paying bigger clients" which you have said is probably a good idea, you NEED to have traffic and people and a community on your website. If you don't make a website which somehow attracts some attention, you can't attract those things.
The teaching part is the part that I would like most of my focus to be on, much like you have said. Since I was young I wanted to be a martial arts teacher, then, when I saw David Belle, I wanted to adapt my wish for martial arts teaching to Parkour teaching combined with some elements of martial arts, yoga, and other things that I feel are "life beneficial". If it is necessary to exploit some big company to do this, for instance Adidas logos on the walls of my gym gives me enough money to keep it running, then I see this as a necessary evil.
I can see your idea of "do it the slow but right way" ... but the reality, at least in any US city, is that you need LOTS of money to have a place to train people. Yes, I would do it just in a park for free, or in a rented space, saving the "business start up cost" ... but all of those things are very limited in what you can do, what you are allowed to do, and in building up a school which will support a living.
As for being a banker, I am actually a computer geek. I have a stock broker license, but I work in technology, no actually with money. but, more to the point, my wife has a very good job, I am lucky for that, but I feel it's pertinent to this conversation because it does relieve much of the strain of me needing commercial support to pursue my ideal career. In other words, I don't have to make that much to make an acceptable level of comfortable living for a family.
This however doesn't take away from the very high cost of rent, insurance, and other things which are very necessary, especially in the US, especially in 2006. Lawyers, accountants, all these things are necessary. Permits, licenses, all necessary. You can't have a business here without, and of course then 30% goes to taxes.
So, my point in this long thing is that if I thought "the slow way" would work, I would do it, but I don't feel that reality allows for this. If I won the lottery, I would still make the T-shirts, because I make them for people who want them, not for myself, and not for the $6. Believe me, my time is better spent doing other things from a monetary view.
If I won the lottery, I would open a gym, no sponsors, but then if I found a backpack that I loved, I would show it to people and offer a way for them to buy it if I thought it was a good product and I could get it for them cheaper.
When I was with UF I didn't sell Jump London DVD's to people because they were cheaper on amazon. But then when Jump Britain came out I was in the US, and I could save people $3, at the expense of about 15 minutes apiece to myself. Not a good business venture, but something I considered to be "helping people get something they want".
So this is where I see more of products working into it than your plan. In an ideal world, your plan would be my plan

I have also yet to meet David Belle as you have pointed out. I have an email conversation with Joss in which I have asked to meet David when he is next in the US. I cannot afford the time or money now to go to France, and I have not had the privilege of talking with David directly. I also am horrible at trying to learn French, so there are some obvious limitations there.