If you just take the 13,835 financed at 6% you are adding 83 dollars a month. so a double whammy.Now, lets consider if rates drop to 5.5% in 24 months (not a prediction just a what if) and you could have refinanced at a much lower costs then the above scenario in what you paid in pre-paid and additional interest. on the other hand, if rates for your same scenario after your 5 year payback period is 9, then you will have an asset with a much lower then current market rent.  

For this I’ve taken the payment amount of the second loan and included it as an additional monthly expense.

There is no additional valuation for the STR business.In the end, past performance is not an indicator of future success.

Additionally, understanding the rights and responsibilities of both tenants and landlords under this program can foster better communication and smoother interactions.

I would have contacted the locksmith tech to get additional details before assuming it was tenant damage.

When you move forward, they should provide proof and name you additional insured.

When you hear something STOP, think on it, ask if it makes sense, then SEEK OUT additional info, seek out CONTEXT.

However, in most markets I would assume an additional full bathroom would not only command higher rent, but would increase the equity and appreciation.

Here in FL a pool trumps all and having a spa feature built in offers additional ROI. 

You can assume about 1% in closing costs in addition to commissions so you're starting around 7% before the seller gets any cash at closing.