You should check with a title attorney to be sure as laws are always subject to change, however, I believe this first right of refusal only applies to Baltimore City, not the County: Under Code §6-1, before title to any single-family residential rental property is voluntarily transferred, the tenant of that property shall have the opportunity to purchase the property on terms considered reasonable in the residential real estate market.I would advise him to give the tenants notice, move them out, take care of deferred maintenance, paint/carpet and sell the properties vacant.

In the City's Zoning code, you can look up the R2 and find what is required and/or what is allowed with this zoning.  

This may include, but is not limited to, property type (duplex vs. tri/quadplex vs. commercial), price range (max price), location (zip code), condition (Class A-D) and profitability.Good luck!

Not knowing if there are tenants or if it is empty, the condition, if there are any code violations existing, if you are assuming a company name that holds the property and if so, the standing of that entity as well as contingent liabilities, what kind of municipal requirements there could be like registration as a landlord in that jurisdiction, or of any other details, I really can't tell you what you need to do first.

These are professionals with additional training and a stricter code of ethics.

The 4-plex needs work to get up-to-code, while the duplex is actively rented (both sides).

There are hot/in-demand areas within that area code, but buying a property at a low enough cost to have room for immediate return is going to be tough. 

Half of the ZIP codes across the Philadelphia market area recorded an Index in the High category in June while one-third were in the Moderate or Steady category.

If you want to do some research on your own from the Lawmakers, start here:IRS - Retirement Plans Published Guidance   (Code, Notices, Advisories, etc.) 

The 18" or lower glass code is all over.