It gunks up when the blade gets too hot. If you are cutting thinner plexiglass go faster. If it is gunking up try going a short distance and backing off. I cut 3/8" thick and had to do that while blowing on the blade to keep it cool.
To the best of my knowledge; YES
I'm not sure. If you only had a few to cut it would probably work. It might not cut thru to the other side of the rail. The fence installers use a circular saw with a plywood or fine tooth blade.
Should work fine..