I have about 25 sheets of Fabral MightyRib that I need to cut.

http://www.fabral.com/products/mighti-rib-pbr

Some, I need to cut in half on the ninety, others, I need to cut into about
two feet long pieces, with one end diagonal.

I have a compound radial saw that I think could be set up on top of my 4' x
10' welding table, and bolted down. A feed made up of roller stands would
hold the material, and it could be clamped in place.

A metal cutting blade would have to spin slower than the speed of this saw.
Can I use a dimmer to slow the blade down, or would that screw up the saw/

Any other ideas how to cut these? I do have a DW890 sheet metal cutter, but
where there are ribs, it will not follow the contour very easily. I COULD
use a 7" circular saw at those points, it would just be a lot of work.

And what about kickback?

TIA

Steve