@Marty Gold it is important to make the distinction between a traditional mortgage compared to a commercial real estate loan offered by a portfolio lender.  

A traditional mortgage lender will only (as far as I have heard) lend on a property in an person's name (no LLCs).  

If it is a single family home you may be able to get as much as an 85% LTV using a traditional mortgage which will have favorable rates and terms than attaching a second to tap equity for the other deals.  

Our first duplex was bought with a traditional mortgage with 25% down at 4.2% since it was an investment property.

@Christian WendelboeIf you’re having trouble deciding whether the investment of getting a license is worth it or not, then perhaps it will be helpful to receive a detailed analysis of the benefits.

The changes were incorporated to provide new rights and legal remedies to traditional residential owners, but some of these same changes will now negatively affect “bulk owners.”A bulk owner is a person who acquires more than seven condominium parcels within the same community.

(Principal,interest, taxes, and insurance) Usually with traditional financing the lenders has it all handled but what do I do in a seller financing situation??

A traditional lender will allow you to borrow against the equity of the home.

Quote from @Christian Cambridge: I’m reaching out for guidance on purchasing a 3rd property.

Since you are not using a traditional lender; you can tell the private lender what you propose and then negotiate out the details.