If you choose to run a traditional PPM (proportional-pulse modulation) FM radio system, I think you will find a high degree of interchangeability of components. The main issue with receivers and transmitters is to match shift schemes (+ or -). Many brands will work with each other, and some of the newer receivers will automatically detect the transmitter shift. When selecting a channel crystal for a different brand receiver, it is probably best to purchase the crystal from the receiver manufacturer to ensure that it is on the correct channel frequency. (I recently learned this the hard way. [&:]) Different manufacturers might use different mixing schemes in their receivers. There are many excellent FM receivers available that have gotten good reviews. They are extremely compact and inexpensive. Servos are probably the most universal component.

Motors and ESCs are basically brand interchangeable as long as you match brushless motors to brushless ESCs and brushed motors to brushed ESCs. You must also ensure that all the components of your power system can safely handle the amount of power required to fly your plane. I think you will be amazed at the number of options you can choose from.

The number of batteries you need will probably depend on the power requirements of your plane and your style of flying. Aggressive, aerobatic flying demands considerably more power. However, 3 or 4 batteries, if they are conservatively matched to your power requirements, would probably give you satisfactory duration. You should be able to realize 10-15 minutes per battery, especially using lithium polymer, and that gives you 45 minutes to 1 hour of flight time, even assuming you are not recharging as you fly. There are many variables to consider here, and you will be able to make this determination as you learn more.

There is a wealth of information on this site, and I highly recommend reading the stickies in the various categories. I think you will find yourself flying much more on electric. Good luck with electric flight.