I didn't know if I should separate it or not, so I didn't.

I do not yet have an LLC set up for the property and have been putting all of the money through a separate checking account set up just for that property and will move it to an account held by an LLC later on.

Are they all separate?

Start repaying the loan separately. 

That is incorrect - 4+ units don't need to be filed on a separate corporate tax return.

I want a clear separation of business debt and personal debt (I won’t have any at that point) if possible.  

Did you comingled the funds and expenses or do you hold a separate bank account?

Plus, if you create a multi member LLC for each buy and hold deal, each deal is separated from the other and has its own set of books, bank account, etc.

@Steve Salisbury forgot to mention make sure the meter main has 2 separate breakers dont double lug :)

ideally there are separate meters for each unit so whomever is living in each unit can pay their own utilities.