If there is a website out there that's "up to date," I'd be a little wary of the advice, personally. That would mean the author is spending all his time maintaining the website, and not using the technology. What kind of advice would you expect from someone who isn't actually out there and active in the hobby?

Your best learning tool is online forums like these. The information comes in small easily digestable bits, instead of all at once, AND it's always up to date. Any book would be woefully behind the curve by the time it makes it to print. Magazines like Quiet Flyer have technical articles as well.

C is a very simple concept, and probably one of the first things you should learn about. It's merely the Capacity of the cells, and is used to describe the charge and discharge rates of the battery. When you see something like "1C charge" it means you charge at a rate that is equal to the battery's capacity. A 2400mAh cell would have a C value of 2400mA, or 2.4 Amps. A cell rated at "10C discharge" is capable of sustaining currents 10 times its capacity. The same 2400mAh cell would be capable of discharging at up to 24 Amps without sustaining damage, were it rated as a 10C cell.