I want to construct a steel road bike frame in the future, and I want to braze it. I have no experience with brazing, but I have time, patience, and some money to spend. I plan on fillet brazing my frame for two reasons: it just looks sexy, and it seems easier and cheaper to practice than lugged brazing. Not that it is easier to do than lugged brazing, just easier to practice since one doesn't have to buy a bunch of practice lugs and stick to certain geometries.

Anyways, I plan on buying some steel tubing and some brass filler rod, and start mitering tubes and brazing them into fun and interesting geometrical shapes. My questions for you gentlemen (and women) follow thusly:

In regards to the tubing:
I plan on getting a variety of diameters of steel tubing. Is there a right or wrong kind of steel tubing? What is a good wall thickness to approximate a bike tube? Basically, what should I be looking for when i go to the metal shop to purchase practice tubing?

In regards to the filler metal:
I looked around and couldn't find any SPECIFIC recommendations for filler metal. What exactly should I look for in brass filler? Any good brands, or does it even matter? I know the filler is made for specific applications, and I don't want to waste a lot of money on something that I don't need. I hope wherever I purchase the stuff there will be a knowledgeable salesman, but I would like to have a grasp on what I need before I get to that point.

In regards to the brazing process:
I found a few decent guides to the brazing process, this being the best: http://www.bikewebsite.com/weldbraze.htm (the fillet brazing instructions are at the bottom). I think I have enough of an idea of how the process works to start practicing it, but I have a few questions that would save me some time if anyone could answer them. How much does gravity affect the braze, meaning if I am brazing two tubes together, do I have to rotate them as I go along the joint so that gravity is always pulling the metal into the join? Or do the metals stick together enough that rotation isn't necessary?

I would love to take a class on fillet brazing alone, but I am having a hard time finding any in my area. Where should I look? I don't know of any bike frame builders located in Atlanta I could learn from, but I would love to even just watch somebody do it. Are there any other trades that fillet braze tubing? Even if it isn't for bikes specifically I'm sure I could learn something.