Speaking especially to fellow California-based investors, viewing this excellent post as exposing "Baltimore specific" problems would be inaccurate. 

So the tradeoff becomes creating a sufficiently high rate of return, while also not exposing yourself to an unnecessary amount of risk. 

With the MLS you have the listing agents entire sphere of influence being exposed to the property as well as the sphere of influence of every other realtor in the area.What is it that your friend dislikes about the listing agent?

It’s just uncommon for real estate agents or people who haven’t been exposed to creative financing.

Definitely recommend househacking as a first deal as it exposes you to a lot of the aspects of real estate investing.

Are they doing everything they can to expose properties to the widest possible market?

You're reduced leverage allows you to make a profit when you sell a property from your portfolio and you are less exposed in a falling market. 

With less DP, you should expect to be more exposed to risks (ie - less cashflow), but the ROI will much, much greater because you're only putting in 3.5% vs 20% DP. 

If you provide a grill, make it a propane grill and keep a spare tank at the house.  

A line of credit is great to have in most cases, as it exposes the borrower to more opportunity, should something arise.