He doesn't have a website. 

These are the keywords that stand out to me in your question:sources, websites, best deals, systems, step by step, factors.You are focused on all of the wrong things.

We advertise on Furnished finder, zillow and our own website. 

There is a free website that I use to find the estimated short term rent based on Airbnb data.The same information you can get from airdna but you need to pay for that service.

If a person doesn't fit into one of the two categories below, what would the point of posting on this website be?

Here is the link to the website. 

Recommend you Google "Cleveland lead paint instpection" and read what it says on city website.

Would definitely outsource for liability purposes 

Out of the 20 letters I've sent, I've had 1 guy get back to me and we were in discussions but weren't able to find a price that worked for the both of us.The issue is that I only have a few houses on my mailing list so far (just places I've walked or driven by that caught my attention), and blindly searching every street and address # to see which houses are actually legal multifamily will take forever and doesn't seem efficient.I know the data is publicly available, I just don't know how to aggregate it in a way that would be efficient and useful for blasting out marketing mailers.Are there any websites that can pull massive lists of all multifamily houses in my area?

For your property websites, weather if its a direct booking site or not, what website builders are you using?