1) how many possible true individual channels can you have?

I have read about all the possible inputs but want to be sure if you can actually use all of them individually at once in the mix.

the reason i ask is most manufactures advertise 16-20 channels and count stereo channels as 2 channels so a 16 channel board is really a 12.

so basicly if i have 12 low inpedence and 4- 1/4 mics i could use all individually in one mix.

The M20d has 16 separate inputs that can be configured in either mono or as stereo pairs. In addition there is a stereo only input (17/18) and the internal media player (19/20)

2) i see how you can link 6 two L3t speakers together and use a mic in both mixers and be heard in both..

   So if i have a link 6  system set up with a L3t as a monitor can you plug a mic into the L3t and send the signal to the board?

and if you can how many different mics can you do this with. It would be a nice feature if we had all L3t as monitors and be able to run the cord into the monitor in front of it, rather then snake it to the board.  even just 1 or 2 would be nice.

It does not work that way. The microphones have to be plugged in to the mixer. Good idea though.

3) there is enough computer power in the mixer to actually run the 16 full channels with indvidual gates reverb delays and comps on all?

Absolutely. You can have 20 channels (inlcuding internal media player) with eq, compressor, feedback suppressor, dynamic eq, deesser, gates, HP filters and 4 global stereo  effects (delays, reverbs, chorus, doubler etc.) and eq, limiter, dynamics and filter in all outputs. No problem.

4) using the link 6 setup is it possible to run a sub in the monitors mix?

If you mean configuration where 1 monitor is a combination of a L3 and a sub you would use the analog out to go into the sub and from the sub you connect the top with line6 link. This way the crossover works correctly.

5) will there be in the future a bigger channel version or a addon extension pack to add more channels?

I can not really say something about this.

6) if i have read all correctly I could mic/line in 16 different things, mixer them seperately as we play, and record the 16 different tracks /waves individaully to a sd card which i could transfer to a PC with a Sonar etc type program for remixing?  

Correct.