Be certain you've fully evaluated your cash flow by doing a cash flow analysis.I leave it to you to confirm you've taken in consideration the following potential costs: CapEx, maintenance, property management, water, sewer, trash, vacancy, turnover, taxes, insurance, etc.

To confirm, did they pay timely and what kind of condition the property was left in. 

Can you confirm if this is correct?

It also confirms the amount of security deposit and the lease ending date.

They have no 2-factor authentication and don't email you to confirm that you want to update your login, both of which I'd consider industry standard these days.

I'd recommend starting with the lower hanging fruit than a large basement reno - if your comps are close but don't quite get you to your number.Finishing the basement (with proper egress) could push you over the top, but confirm with an appraiser first to ensure it counts.

For example, at the start, do you confirm if all persons in the house are aware of your presence, and do you ask if it is OK for you to open bedroom, bathroom and closet doors?

This way, if vacation rental management becomes too demanding or isn’t feasible, you have an alternative strategy in place.Make sure to confirm that the HOA or association allows rentals at all.

Have you confirmed with BDS that parking will not be required? 

I would recommend consulting with a tax professional to gather more details to confirm this based on your situation.