Okay , you need to think about something first.
The fee should be a lil less as compared to the online fee when you sell the bitcoins to someone because that is what will make people use it more.
At the same time there have been problems with the ATM when the person transferred the money but had to wait a lot lot more than the normal waiting time therefore you do need to thinking about solving such kinds of problems instantly.
It is rather a good idea but you need to improve the existing idea of Bitcoin's ATM .
This is a good point, I'll ensure that there is always coin available for immediate transfer, the rates will be competitive, customers probably won't be able to buy massive amounts, both for security purposes and in line with KYC/AML and statutory reporting limits.
I support the fee point. Even though I've lived in places where there are Bitcoin ATMs and sometimes I needed to exchange Bitcoin for fiat, I've never used them. The main reason is that the fees are pretty much always higher than if one decides to exchange online. Limiting the amount one exchanges seems fine, and perhaps the fees should not be less than online. They should be about the same, and this could already attract people. Moreover, I am sure that many people are unaware of the existence of Bitcoin ATMs, so make sure people know it's out there, and the conditions of using it. Good luck!