If one design is your desire, H16 is a great choice. You will have tons of folks that can help you be fast.
1. Yes, it can pitch when pushed on a reach- your crew needs to be on the job and playing the jib to keep the bow up. Both of you need to be on the back corner in a breeze.
2. depends on total crew weight. The boat is over-endowed w/ sail area vs. displacement which is one reason it is so much fun!
3. The DPN number reflects the thousands of excellent sailors optimizing the boat over many years. P16 is basically as fast and has more bouyancy in the bows. The 5.2 is faster in my experience.
4. ~300lbs, w 285 minimum.
It has been a long time since I raced so be sure to get info from current racers.