I don't have it all figured out either. I've only been flying for almost a year. But I can share what I do know, and hopefully I can keep it simple and helpful.
According to David and Bixler, you start with the propeller, then you find the right motor for it, then the right ESC, and then the right battery.
You can use a simple thrust calculator to have a rough idea of what to expect thrust wise from any given prop. Here is the one I like to use:
http://personal.osi.hu/fuzesisz/strc_eng/
Also, when looking for a prop, it's good to know that long props give you more pulling power. It's like riding a bike in first or second. A short prop can handle spinning faster, but it's like riding a bike in tenth gear. The long props get the plane to full speed right away, but can't go very fast. Short props can go a lot faster, but takes quite a while to get there.
I found what David said in the third podcast extremely helpful. He said something like 2 inches on the pitch of the prop is equal to 1 inch on the length. As far as the load/resistance the prop creates on the motor. Basically, if your motor can handle a 9x5 prop, then if you want to go up to a 10 inch, the pitch needs to be 3 in order to equal the same load/resistance/performance (watt wise). Or you could drop down to an 8x7. At least that is my understanding of what David meant. It doesn't sound quite right, but close.
Finding the right motor can be hard. Especially if you're looking for the most efficient. I think all you can really do in that regard is read reviews of a motor. See what other people got out of them and with what setup. You can buy a motor and then find out which prop size is the most efficient for it, but that might not be the right prop for your plane/copter.
Basically look for the KV rating you want out of the motor, and then find one that can handle the prop you want.
For ESC and Battery, you need a watt meter to know how many amps the motor draws with that prop. Don't worry, I don't have a watt meter. I base what I use from what other people do and what is recommended for the motor. But usually, I just use a 30amp ESC regardless. I'd rather have an ESC that can handle more amps than what is used. And as far as batteries, I always buy the highest "C" rating that they have for the battery I want. Yeah, I end up spending more. The last battery I bought was $20 and if I bought the one with the lower "C" rating it would have been $10. But I figure it's worth the extra money to know I'm not going to overdraw the battery and kill it. It's an investment for a longer lasting battery.
I hope this info was helpful to you. It can be difficult and take a while to know what the right setup can be. I know I've overheated a motor or two and I burnt out an ESC.