Yes, it suitable for exterior use with a couple of qualifications: 1. Since it is made using finger-joints it shouldn't be used for structural purposes, I would recommend it for trim use only. 2. And, if it is painted (and kept painted) with a quality exterior paint so water can't get to it, it should last outside.
Yes, made it easy to paint it the final color!
It comes with a flat latex primer so as long as the oil is compatible with a latex primer, yes.
about 22 lbs per a board based on the same size pine dimensional lumbar.
Easily with a power saw. A little harder with a hand saw.
About 3/4 x 7/5 x 8f.