The only thing you need to do is deposit the check and track your income and expenses for taxes 

I believe this damage is due to tenant negligence and am considering withholding a portion of the security deposit.

Some tenants go directly to my bank and deposit their rent directly into my account. 

I've seen landlords get stuck with a chargeback on CC deposits and rents for various reasons.Some have suggested a landlord send an authorization form to the prospective tenant for their signature to avoid any shenanigans later.

The deposit and last month of rent is only $2700.

Outline what happens with possessions and deposits. 

Unless your seller is savvy or there are multiple offers on the property, you should have no problems with placing an Earnest Money Deposit in escrow. 

At closing, you'll get the security deposit and any rents already paid for the remainder of the month transferred to you. 

If possible add to security deposit for this 2) they pay water bill over X or they take over water bill split % of SF Ie 55% A 45% B. 3) they maintain liability insurance if anyone hurt/drowns in pool and you are named additional insured.Remember you will be sued too if anyone drowns in the pool.

Obviously speak to an attorney, but document all fees for cleaning, and take from the security deposit.