1. in pro tools le can i track with a plugin(say a eq on a kick drum)and have that plugin go "to tape"?
Yes. This does not work in "Low Latency Monitoring" mode, but in any other mode, this works just fine.
2. can i insert a plugin(say a compressor)to the 2 mix buss for final mix? how about a hardware comp on the 2 mix?.
Yes and yes. To use a plugin, just put it on the master fader. To use a hardware plugin, set the master fader output to one of the pairs of outputs (3-4, 5-6, etc.), run that output into the hardware, run the output back into a pair of inputs (3-4, 5-6, etc.), and record that input back to a stereo track.
3. can a sepreate q mix be made for the people tracking with headphones? (kind of like mackie's "mix b" section).
You can actually do as many submixes as you have outputs and available busses. Practically, you can do 5 submixes (each track has 5 available sends), without getting into some complicated internal routing. If you need more than that, PM me. For each track that you want to be part of a submix, add a send, route that send to a bus, create an aux channel for the bus, route the input of the aux channel to the bus, route the output of the aux channel to a stereo output pair. Then mix levels and pan accordingly. (If that sounds complicated, once you do it once, it will seem very simple.)