How to know when to expand? How much cash on hand per property?

[George Leeman]

Does anyone have any general requirements for when to expand?

For example how much money should you keep on hand per rental property in order to be comfortable to handle repairs?

What should your overall debt to cash ratio be before you are comfortable with purchasing another property on a mortgage?

How much emergency living/life cash should you keep on hand to be safe?

How much should there be (if any) in a emergency realestate slush fund on top of your set aside basic amount of cash per property?

Any suggestions on things like this? I want to do this properly.