The biggest lesson, which I learned early on: get clear on the type of property you want to buy, then tell everyone over and over again.

Are there specific considerations, tips, or challenges I should be aware of in these areas?

@Sham Haile you should look up the Tenants Union & RHAWA websites to review the notices and requirements for how notices need to be provided to tenants when a seller intends to sell a property. 

Read "Long-Distance Real Estate Investing" by David Greene.

Is it possible to sell or refinance one unit to pay the other off completely. 

I wish you the best in investing journey.

Approximately 30% of this area is made up of vacant lots, creating a prime opportunity for real estate development.Griffin Modern is taking full advantage of this landscape, acquiring lots for under $10k and developing homes targeted at young, first-time buyers as well as investors.

Look up @Derek Sherrell (ThatADUGuy).

Have you read the OREC rules from top to bottom?

If the police came they probably did not come and document the damages, get the report.