Hey, I'm one of the people behind Ask Mr. Robot. We've done a lot of research and see these questions a lot, so I wanted to jump in.
1. As Xenocastra pointed out - SimC will make it seem that haste is better or equal to mastery, but Mastery works better with multidotting. We also got the same results from SimC, and we also put mastery above haste since burning targets with AoE heavily favors Mastery.
2. Shauni points out that a lot of people provide stat weights that are generated off a BiS set of gear. At AskMrRobot, we wrote a program that interfaces with SimC: it runs through all sorts of gear levels with various stat weights until it converges on a stable set of weights. We then evaluate those weights to make sure they make sense. And in the case of Affliction locks, we decided Mastery is > Haste because of the point made above.
3. Regarding Mr. Robot devaluing hit. You actually gain DPS by valuing other stats higher with an Affliction lock. But, we know a LOT of people really want to be hit capped so we recently added in a hit cap preset. Just click on the drop down box in the action bar and choose "PVE Hit Cap Build."
Here's a link to the default AMR stat weights for Nekrotic: http://www.askmrrobot.com/wow/gear/4...5-a08eaac34046
Here's a link to the HIT CAP build: http://www.askmrrobot.com/wow/gear/e...9-410255f4dd74
Lastly, I recently posted some more info about how Ask Mr. Robot works, where we get our weights, etc. You can find that info here: http://blog.askmrrobot.com/2012/10/h...ptimizer-work/
Might be ideal to switch out Windsong for Power Torrent for the time being since it doesn't proc on DoTs, no?