I keep replaying this over and over again. It's really fun, especially waves 9+ when it gets noticably more difficult. I managed to reach wave 11 once.
I have a few more things to report.
First, when a soldier gives me +6 ammo, UI gets updated by 5 bullets, after I shoot the next time.
Second, I'm not sure, but I think the business suits have 1hp instead of 2 like the zombie info screen says.