Yeah I do include the chance in the formula, I also add 0.0005% for each chest and each breakable, cause they all spawn ghosts with a 2.3% chance (according to my data) and I just assume that they have the same loot table as the boss giving a total of 0.0005% chance per chest or about 1% additional drop chance per mission, bringing the finla chance of getting a pink from a mission to be 3-3.5%

In terms of prices, they will get lower and lower no doubth, and the potential gold per hour will get less and less as more people begin doing that same thing. But when we get new level 30 items with new missions and the new demand for those items, this starts to be a very effective money making method.

As for the best skills, best spec, best strat and best stats, they really don't matter that much, it's really not that hard to complete any mission in 3 minutes, especially with your friends, if you complete it faster then you just gonna have to wait in the end for your energy to regen.