At 16, I was just about 6ft and weighed 75kg and I played blindside flanker, though that's because I was very good at tackling and knew how to scrum properly. You'd have to be a back with your weight and height really. If you were exceptional at tackling and quick, you could make it as an openside, but you've not put it down. If you're a good passer, that likes to command the forwards a little bit, and doesn't mind getting into the opposition's faces a lot - Scrum Half If you're a good kicker - Fly Half If you're rapid - Winger All rounder - Centre A VERY good catcher and tackler - Fullback
Depends on speed, agility, fitness, strengths etc But id be playing you at Fullback, Wing or centre. Possibly five eighth