Shoot it a bunch and then see what you want to do. I've changed the trigger connectors on the Glocks I owned (all in .40 or .45), but I have fired others belonging to friends and family that I wouldn't have done that to.
Having some kind of light is a good idea, whether you attach it to the gun or carry it in hand. Give some thought to how you plan to employ it, and that will help you decide what kind of light and sighting options you want, if any.
The greatest advantage of a weapon-mounted light is also its biggest pitfall. You are pointing a loaded gun wherever you point the light, whether it's at a bad guy creeping through your living room or at your kid going to the potty. Your personal circumstances will decide.
"An armed society is a polite society." — Robert A. Heinlein
"After a shooting spree, they always want to take the guns away from the people who didn't do it. I sure as hell wouldn't want to live in a society where the only people allowed guns are the police and the military."
— William S. Burroughs