How to add feature to only accept certain amount per form/date

How do I add a feature that only accepts so many per date/event?

You will have to set up the field using our widgets that would allow you to set a limited quantity. The below guide should help:

https://www.jotform.com/help/426-How-to-Setup-a-Payment-Order-Form-with-Limited-Stocks 

With regards to your question about the signature, I'll give you the answer in the new thread here https://www.jotform.com/answers/1792310.