They make both a sq edge product and a grooved edge. you start with a sq edge at the outside of the deck , switch to grooved which goes down with a clip and screw system. Some folks use the fascia boards up to cover the edge, its an option. There are a lot of tutorials on the Trex website.
It cuts with a jig saw, but buy the best blades you can get and be prepared to change them when the dull (fast) . Same with using a circular saw or miter saw, just budget for a new blade and it will be useless for anything else once you have cut trex. The proprietary mix of plastics and wood fibers is very dulling.
It gets hot under bare feet, I've had 500sq ft in the back for 20yrs. Its no worse than a Caribbean beach, flip flops.....