You want to lift something up but not pay someone else to do it first. 

In my state that would be an expensive change as I would be paying state transfer tax on the move along with other costs plus I would need to consider whether I wanted to buy title insurance on the property for the new LLC.

Depending on how you are planning to pay your friend  the profit out of the transaction.

IfIf you do not know what you're doing with accounting, which most people don't, I would recommend that you simply bite the bullet and pay someone to handle it.

He has also mentioned that his job has been paying him late here and there.

I pay around 2400 as rent and I've calculated my monthly expenses will be around 3700 if I buy a condo. 

Should I pay her more $ for longer stays like this or just pay her the same fee? 

I can use those as the legitimate reason to deny the application knowing that my real concern is their inability to pay the rent due to maternity leave.

You can look at a deposit insurance that the tenants pay to offset repairs and fights over their deposits. 

It's going to be nearly impossible to ballpark based on what others might be paying.