TTL just means "through the lens" (metering and controlling the flash power)! Has nothing to do with compatibility.
The Yougnuo wireless kit you have are called transceivers. They work as a trigger, and a reciever. So, you need one on your hotshoe and one for each flash you intend to use off camera. The on on the camera will act as the transmitter (you can put one flash on the unit on the camera hotshoe, but I believe you want 2 off camera flashes, so you need 3 transcievers). And the 2 off camera will act as recievers. You can actually have as many as you would like. Now if you don't have the 2nd flash yet. They do make flashes that have the wireless installed inside of them. It would a a Yongnuo flash. And it would say it's compatable with your transciever. That may be less expensive than getting another transciever and flash.
As for the Neewer flash. As long as it's a hotshoe compatable flash that works with Canon it should work. But it appears that you have to control flash power manually. For a set up like a photobooth that would be no problem. As once you get your flash values, you don't need to change them. As long as people are in the same positions.
If you have not done it yet. Please go over to Strobist.com and start with lighting 101. And follow each subchapter. You will get a much better understanding of using flashes.