I've been working on implementing these set bonuses into simulation craft, so I've spent a lot of time on the 2-piece bonus. so here are a few findings or confirmations of things that were announced.
The Thunderhawk only casts Lightning Blast
. At low haste levels, it casts it 5 times. As you increase your haste, the chance to get 6 casts increases. At some point, you get a chance to have 7 casts, and so on. I'll get back when I have computed values.
does not scale with Attack Power, so it always does 20k damage, in average. If you are playing a Beast Mastery Hunter, then it scales with your Mastery, so if you have 25% Mastery, then your Lightning Blast will always do 25k damage, in average.
can critically strike, according to your own critical strike chance. It can also miss, regardless of your chance to miss, so we believe that it may be a bug.
Also, the proc for the Thunderhawk is on a set value per minute: 0.7 PPM (Procs Per Minute) for Beast Mastery, 1 PPM for Marksmanship, and 1.2 for Survival. I still want to test whether having more Haste Rating causes the Thunderhawk to proc more often, but it is hard to get conclusive data (with 1 proc per minute, I'll let you judge how long I need to test