1. Channels go like this
1 channel: mono (monoblock)
2 channels: stereo sound, left and right
4 channels: stereo sound still, but better wiring for 4 speakers. (allows fading)
There are other types but these are the basic
2. Ohms just means impedence, the lower the Ohms, the less resistance, the stronger the power. If an amp is stable to X ohms, thats the lowest it can go before you run into problems like the amplifier going into protect mode. if you don't need too much power, try and keep the amp in a higher ohm load, 4 ohms sounds much cleaner than .5 or 1.
3. RMS just basically means the continuous power output. This is the main number you always want to look at when buying anything for car stereo, this applies to amps, speakers, and subwoofers alike.
As far as amperage, all electrical components are relative, watts, amps, volts, ohms. Google up how electricity works and for the equations to relate them all.
4.Ported = louder bass at the cost of a more linear output slope.
sealed = not as loud but much more accurate and flatter output.
Bandpass = focuses on a frequency range
Some people really don't notice the difference and some people prefer one over the other and swear there are other differences. To me, ported just sounds a little warmer, I prefer it as long as it's made right. Bandpass to me sounds terrible, its really only good for a very narrow (in comparative terms) in the output sound spectrum and doesn't sound too great. But when its used for a specific music type (rap) it sounds great and will produce a lot of sound.
5. Ehhh, too many to list. and it really depends on what you're trying to accomplish.
One major Do: upgrade wiring (google: big three (in car stereo)) whenever adding a stereo.
One major don't: If you're into SQ do not buy eminence
You'll have others that will give you better answers, but i'm quicker
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