Greemology says:
Will Quick Draw work with Rock Throwing like it does with normal throwing when I gain iterative attacks at level 6?
Also, how do you feel about the
Two-Handed Thrower feat from Ultimate Combat?
Sorry, I wanted to look into it all before I answered, I'd say it'd be fine, feat working as anticipated included.
Where I'm gonna have the issue is having plentiful ammunition available. It hasn't really been an issue up until now because you've been making one attack. The way I envisioned that working is you see a sizable rock in the dirt, yank it out real fast, and throw it. I don't see that working in all environments and I don't see it working in the quick succession that would be required for multiple attacks per round. At minimum, I'd start needing perception checks to spot them and strength checks to jerk them out of the ground fast enough.
Obviously, if it's a rocky area or there are suitable items to be thrown, no issue, go off fam. But if you're in a field or a snow-covered area such as this, I start to have issue with finding such things simply lying around plainly visible and in reach.