I've got long fingers and don't shoot much with gloves. The stock grip was too thin and put my trigger finger too far into the trigger guard. My accuracy improved when I bought a magpul MIAD grip that was larger. It also has a compartment in the handle for extra batteries, rounds, or an extra bolt.
Also, if you hike much with the gun as I do, you'll want to find a decent sling setup. I've got a magpul MS3 with a Troy mount at the base of the buffer tube.
I don't bother running a light as the added weight wasn't something I wanted when hiking around. It really depends on what you want to do with the gun.
I've got two optics setups that I used for different situations. The first is an Aimpoint PRO with the Larue mount, and Magpul MBUS in the rear. Right now the gun is set up for long range shooting. Here is what it looks like now:
What you really should do it just shoot it and see what you want to change. It all depends on what you'll be doing with the gun. There is no right answer for everyone.