Some EQ Questions (referring to Sonitus EQ plugin)

I've started fiddling around with the Sonitus EQ now to try and get to grips with it, at the moment applying it to individual tracks for their initial 'clean-up'. These are going to be really daft questions, but because sometimes to my untrained ear I don't really notice much of a difference (or any) by moving some of the faders, and because whilst I can play around with it I don't actualy UNDERSTAND what it is that's going on (and why), I just want to check something...

1) Are the lower numbered frequencies (e.g 60hz) the 'higher' pitched parts of the track or the 'lower' (if I pull the lowest numbered freq right back, I don't notice much difference, same with the higher numbered ones - it's only when I start playing with the mid-ranged that I notice a substansial difference)

2) If I put something like a 'high-pass' filter on at say 165hz, will that cut off all the signal that's on the 165hz fader and the ones below it? It only 'greys out' that particular fader when I select these, but I thought the point of a low-pass was to cut of everything abovee that freq range and the high pass cuts of everything below it.

3) If the 1st faders freq column says 100hz, and the 2nd says 165hz, does the first cover the whole freq range from 100hz to 164hz? or does it cover 0-100hz?

4) What's the difference between a peak/dip, a high-shelf and a high-pass filter in real terms?

4) Would I apply EQ before compression or after?

I managed to somehow get a much cleaner and better sound in my vocal and acoustic tracks, but this was pretty much down to luck, because I don't understand what all this stuff means or why it affects the sound