Equalizing is the concept of applying artificial electronic filters to increase or decrease the amplitude (volume) of a certain part of the audio spectrum: The most simple version of this are the classic BASS and TREBLE knob buttons that allow you to respectively increase/decrease the lower and higher spectrum bands. More complex equalizers offer "pass-band" filters that you can adjust to increase/decrease selected bands. Very cheap ones have say, three bands (50-100Hz, 100-300Hz, 300-3000Hz) while better ones will have more precise bands and better range, going as low as ~20Hz and as high as 15-20KHz.
Depending on the need, you can equalize as you see fit. Ever seen those boomboxes with presets like "Rock Concert, Jazz, Disco, Dance, Flat, etc...?" Those are pre-programmed EQ settings. Avoid them like the plague.
When you write music, you want to hear precisely what you make so NO equalizing on your sound output. In my virtual studio however, I do TONS of it on every different channels.
No surround = no surround speaker/setup. You do know what surround is? If not I can explain in technical terms.
Double stereo = Two left speakers, two right speakers. Usually one pair in front and one in the back but both my pairs are in the front (tee-hee)
Flat amplification = I amplify everything, all the spectrum equally.