I’m sure there are several individual cleaners in your area that would love the flexibility and frequency of a quick and ongoing $40 gig. 

There should be some form of regular interest payments that are similar in frequency and rate to what your brother should expect if he were to go to an unrelated party in the open marketplace.   

I'll give a little different take....in my experience once you have a legal lease that you're happy with you may never encounter another legal question ever.The tax issues important in terms of frequency because you'll face them every year and taxes are likely your #1 expense beside mortgage interest.The 2 main keys to being successful are that if something breaks, you fix it for the tenant and the tenant has to pay the rent on time. 

frequency of wild fires?

I look at things in the sense of what is the frequency of which they occur.

I had this one guy asking me if I had "systematized" all the problems of defunct housing down a checklist and a guide and could I share the .pdf with him.But the con artists who sell this garbage housing to newbie long-distance investors must find plenty of takers, because the takers show up here with alarming frequency.

Keep in mind condos are challenging with limits on frequency and duration of tenancies, HOA approval of tenants and often the condo fees kill cash flow. 

Channel, frequency, firmware, software, security settings, noise in the environment, something as simple as moving furniture around can impact coverage. 

You only have their word as to the frequency of flooding and you have no idea why it’s flooding now.

And of course there are all the real estate sales stats like DOM, closing/listing price ratio, frequency of multiple offers/bidding wars, etc.