Well written Matt.

The ESC is choosen by how many amps that the setup is known/estimated to put out and how many volts you will use to put through it (3 cell lipo, 4 cell lipo etc.) Manufacturer ratings will tell you what each controller can handle (check www.castlecreations.com for specs on each controller). When choosing what rated ESC you need for a particular setup, there are a few ways to do this.
1- follow someone elses successful setup (I use the search button alot for this task)
2- Use a computer program like Motocalc (www.motocalc.com) or ecalc (http://www.hobby-lobby.com/ecalc.htm) or even a free online calculator like Pcalc (http://brantuas.com/ezcalc/dma1.asp) *note: pcalc does not have a complete listing of smaller setups
3- Trial and error

Since option 3 is expensive, I really like option 1 and 2 .

The battery is choosen in much the same way. Knowing the estimated or actual amp draw of the power system and comparing that to the Manufacturer ratings of the packs. Then choose what voltage (7.4V= 2S, 11.1V=3S) you need to power the motor with by the manufacturer specs on the motor. You are not limited to one or the other, but one can be more ideal than the other and manufacturers will normally have already tested this for you (ie: check the specs of the motor).

Dont expect to learn everthing in a day. I like comparing electrics to parenting....knowledge is general and ever changing as electrics and kids evolve. I have been in electrics for three years from 7oz shocky's to 50cc conversions and I still learn something new every single day.

You can use this in a heavier plane, but realize that something will suffer. Normally performance. If it is ballistic on a 7oz plane, it will be marginal on a 14oz plane. Kind of like taking a 40 size IC engine and putting it on a 90 size plane. It'll fly it, but not as well as it did.

-Mike