If any bank statement you provide shows a deposit over a certain amount you need to supply proof of where it came from. 

You also can't employ a full time repair person with so few units.For all these reasons this is why a local bank wants that small business because if they only have 40 million in deposits at that branch it is big business to them.

I have an agreement to have 21 days before my deposit goes hard.  

Find out what your "get out" period is without losing your deposit.

Keep the security deposit in a separate account as well. 

Let them know you are a busy man and have only a limited amount of time or a particular time slot that you can view the property.  

If you are doing a Rent-to-own do you charge a security deposit?

If you accept him as a tenant, require an additional security deposit.

.) - they will coordinate with the buyer for appraisals, termite inspections, coordinate with their mortgage lender, earnest deposits, etc. - they will be the primary contact, so after you and the buyer have settled on the price and contact a title company, they do all the rest of the work!

Simply write a check from one to the other and make the deposit.