[RC-Monster Mike]

Chris, There are several hundred posts on this site dedicated to brushless questions as well. There really is no hard and fast rule for selecting a system, but the performance aspects work similar to brushed motors. The bigger the motor, the more torque it will have. The faster the motor (higher rpm/volt), the more power it will have, but at the cost of less runtime (like a mod motor). There is no one place to "learn everything about brushless motors", and while you will certainly learn a lot from this and other forums, experience is by far the best teacher. I use my experience to try to match a system based on the needs expressed by the customer, and I will always answer any specific or general questions you may have before, during and after the purchase. Please look around and if you have an unanswered question, feel free to ask away.
Also, I will further recomend the lehner basic 4200 to go along with the MGM controller for your truck. This has a nice power output and is very good on battery consumption. If your truck can take 7 cell packs, this would probably enhance your driving pleasure as well (the 4200 runs very well on 7 cells with a very nice runtime). When it comes to batteries, a good quality set of batteries is required to get the optimum performance from a brushless system, so keep this in mind as well. There are also a few posts regarding LiPo batteries and a few experienced folks on this forum running them.