Can Quicken Spell be used with spells gained through Qinggong? Not sure since it would normally take up a spell slot 4 levels higher than the level of the quickened spell. Other than that, not a whole lot jumps out at me. Possibly you can do away with Toughness, just depends on the makeup of your party. If you do, you can take Snake Style a bit earlier, but its not really a big deal. I don't dislike Toughness per se, just that in my opinion its a feat whose usefullness will vary from party to party. Certainly the monk can use more HP especially if there is not an abundance of big melee types.
I might also consider dropping Slow Fall, but again its one of those abilities that's definitely situational. It might only come up a couple times during a campaign, though admittedly, when it does come up its pretty dang cool.
What you do have though will definitely work out well, just not sure Quicken will work, though if the GM says yes then run with it! :)
Ahhh well, if you're going to be the tank, then I would definitely feel more inclined to take Toughness . . . every little bit will help.
I agree that Quicken is a bit vague to say the least. If your GM says no, you could potentially point to Quicken Spell Like Ability as a compromise. That gives a limit of 3x per day and requires a caster level of 10 (monk level = caster level for Qinggong monk).
In any event, hopefully your GM will make the issue moot. :)