I believe Costar pricing depends on what market area you want, but for a single license, I'd expect >$500/mo.If you're new to investing, I'd suggest working with an agent, at least until you better understand the process and common pitfalls. 

Some examples are;-County website for actual prop tax bills-Tenant estoppels-Actual utility bills-Bank statements and tax records-Verify insurance premiums with your carrierSome say "Trust, but verify," I say "Trust that someone selling you something will only show you what you want to see.......So verify."

This is commonly called a reverse exchange or a construction or improvement exchange. 

A common issue is supply and demand effected by population changes, construction, economic issues, the job market and location.Personally I haven't seen vacancy issues at this time,  but I have gone through cycles of vacancy issues.

This is a single family home and was originally a primary residence before turning it into an long-term rental.Some strategies I'm considering to grow my portfolio are using a HELOC/1039 tax exchange to purchase a second investment property/multi-family property or refinancing my current investment property into a conventional loan to utilize another FHA loan for a primary residence (with the idea of eventually turning that into another long-term rental).I currently have a 7% interest rate, and am considering refinancing in the coming months if/when the rates drop.

Familiarize yourself with the types of properties commonly financed through private money lending and the current trends in your area.

I have turned 8% ROI into 18% ROI by utilizing wrap around financing when selling, as an example.  

I was on the HOA board of a luxury building in San Francisco and you would be surprised at how many people will let their dogs pop and pee in the common areas (killing very expensive plantings).

There is a high cost to renovating a non-restaurant space into a kitchen, especially if you need everything like grills, hood vents, walk-in coolers and grease traps in floors, not to mention the utilities to service all of the above.

Garden-level or street-level ADUs are common in New York multifamily properties.