The SU 16 is a great rifle, you'll love it. My suggestion is to keep it stock and don't tacticool it up. They're designed for portability and for quick and easy deployment, not as an assault weapon. If you want that, buy an AR type and go all out.
The SU 16 is great for the woods and gives you decent firepower. Mine was accurate, dependable and fun to shoot, a great combination.
As far as ammunition, I used Lake City/Federal XM193 in mine.
If ye love wealth better than liberty, the tranquility of servitude better than the animating contest of freedom, go home from us in peace. We ask not your counsels or arms. Crouch down and lick the hands which feed you. May your chains set lightly upon you, and may posterity forget that ye were our countrymen. ― Samuel Adams