It's only when you're working on behalf of another buyer or seller (which would classify you as their "agent") that you need a license. 

If you do not want to keep the tenant, give them a 3 day notice to come compliant with the lease (i.e. get rid of the pets or get them re-classified).Immediately collect pet deposit. 

If it's unlivable and not ready for rent, you typically wouldn't start depreciation.Deductions- While the properties aren't generating rental income, you'd classify them as investments.

Regarding your question on what classifies a commercial property.

They are classified as Rvs and must be parked in an RV Park, but there’s even a lot of restrictions there.To build an ADU, which is about as close to a tiny house as you can legally get, you need to build on a SFR.

Would you classify this is "risky"? 

For newly constructed, purchased or renovated properties and also retroactive generally over the last 10 years, building components are properly classified into individual units of property and accurate recovery periods for computing depreciation deductions.

Then refinance and take that money to buy our next property and rent out the original, which I guess would classify as a BRRR.I've often heard of live in flips being classified as house hacking - what would be the reasoning behind that?

I am currently renting a property in the state of Colorado that is classified as a single family residential.

I have read from multiple sources to avoid using the real estate SIC code 6531, when registering for a Dun and Bradstreet number, because it is a high risk code for real estate investing.