Our plan is to take her security deposit to pay for the replacement of the carpeting and to write her an invoice for the remainder of the bill and take her to small claims court if she doesn’t pay the outstanding balance.

I'm close to securing a contract on 4 unit property in Middletown, OH.

I understand I’ll have to hire a property Manager, I just don’t understand how security funds are handled Incase of emergency and immediate attention in the scenario where I may or may not be able to reach right away .

The tax lien (also called a fifa) exists prior to the tax sale and is recorded in the county's lien records - it's an unpaid debt secured by the property.  

A mortgage is then filed against the property to secure their investment.

I was thinking about being a real estate agent, but I'm missing social security number, so I can't be qualified as one.

Require a higher security deposit, last month's rent, both?

Your method makes sense for my higher rent units, but I'm not sure if it makes sense for lower rent units, which I'm already requiring first, last and security? 

If I have a tenant move in mid month I always collect a full first month's rent at move in (along with the security deposit).

Aside from that, they're usually much safer than an apartment and offer more security.