The problem is you don't know if someone just made a large deposit to make them look good and then the money is gone after they move in.

If booking direct and he has no reviews I would have him sign a simple lease, do a BG check, and have a reasonable deposit.

I would avoid this if its your first acquisition  but you also appear to have enough cash to complete the purchase without financing so you wouldn't necessarily be at risk of losing your deposit, only incur additional transactional costs.

If you are showing monthly deposits of the same amount each month that are in the amount of a rent, you would need to show where that money was coming from and going to, as in which address it applied to.

I accepted a prospective tenant's lease and deposit after doing due diligence.

In most situations the tenant is 100% responsible for the initial security deposit payment, and any recurring utility charges. 

There are several types of fees on Airbnb specifically: -Airbnb service fee, cleaning fee, extra guest fee, pet fee, security deposit, VAT (if applicable), and local taxes. 

I would charge it now so that it doesn't need to come off the deposit at the end leaving you with more deposit for any other damages.

Our average online rating is 3.5/5, which is 60% higher than the 2.2 star average of traditional property managers.Sometimes we need to make a tough decision in favor of one side of the landlord-renter transaction and at a negative impact to the other side (i.e. deducting security deposits).

It's also wise to check references from previous landlords to understand their payment history and behavior as a tenant.Once all the information checks out, you can proceed to signing the lease and collecting the security deposit and first month’s rent.Good Luck!