Let's break down your equity based on your numbers:Property 1: 6.5% return on your equity (yearly cash flow/Equity)Property 2: 6.08%Property 3: .88%  Property 4: 2.09% Property 3 and 4 are definitely too low of a return. 

Learn about your individual local markets based on your desired home.

If you are going to refinish, what I'd do is sand, clean, and put down multiple layers of oil based polyurethane.I would not stain the wood.

A lot of those older houses have corroded cast iron or galvanized pipes.Asbestos - This was use in many house products all the way back to the 30s.Lead-based paint - This was used up until 1977.  

Some lenders will up to a 95% combined loan to value for a heloc assuming credit and income are strong. 

It gives you a broad base to work from and a substantial range of knowledge when making connections.

If a newbie is investing in Baltimore City, they should stick to the locations where the housing stock is in better repair, the tenant base is better, and where there is rental demand.

I will ask a question based on a few things-does she want to leave because of domestic violence? 

this isn't an option for everyone based on family situation and lifestyle, but I know multiple people who have sequentially house hacked their way to a portfolio of 5-15 units in 5-10 years simply by using their monthly housing payment.

Since no one else has chimed in on this I will play advocatus diaboli here since it’s a topic I feel strongly about.