If deposits are allowed to be withheld to cover for rent owed you are good to go.Read your state regulations, you are required to know the rules governing your business.

A quick rule of thumb to figure out if the rent to earnings ratio is 1/3.

Buy and hold, hard to find 1% rule, best way to make money seems to be the rehab. 

I know in NY there are certain rules utility companies must follow, there could be similar rules by you.

Would it be a good idea to get a hard money loan to rehab a house then refinance into a first time home buyer mortgage program, even if that's possible,  I'm not too sure with the rules and regulations.

Tentatively estimate (for convenience) the 50% rule for expenses.

There are ordering rules to all the accounts for distributions.

Meaning following all the rules re: tax implications, etc.

I'm getting the numbers from the water/sewer/trash people, but since the cost is usage dependent, I would also like to gather some real world numbers, or rules of thumb, in order to estimate these costs on a monthly per unit basis. 

I think Casa Grande is a great rental market, it's one of the only places you're getting at or close to the 1% rule in the Phoenix Metro.