Gang,
I have a couple of questions for everyone about filters.

I'm thinking of buying two or three graduated filters (netural density and a graduated orange). I've used both of these from Cokin in a square filter format with my old TRV 900 (bless it's wonderful heart) and been very pleased.

I found it essential that I can slide the filter up/down to put the graduation just where I need it. So I think I need a similar square filter type arrangement.

I would really like to not spend a fortune on this, as I'm essentially just a prosumer looking to make great looking videos for my friends and I. I'm hoping to do something for about $200 or less.

So, my questions are:
1) what filter system should I go with (a B&H reference would be nice)?
2) Is there one available that works with the A1 Matte box, or do I need to buy another Matte box? Can I just stick the filter on there and not worry about having the matte box on the lens?
3) Has anyone figured out how to mount a filter on the threadless Canon Wide angle lens adapter that we all love.
4) Is there a kit/set that people would recommend?
5) Is there any difference in quality between manufacturers? What can I likely get away with?
6) Which graduated ND filters do people suggest (.6 is Steve Dempsey's choice) ?
7) Suggestions for coloured ones? I really like the graduated orange one I have!

Thanks for your thoughts!!!

Cheers :) D
PS I already bought a polarizer (Hoya Super HMC), that I'm pretty happy with.