John Hickey congrats on buying a cash cow.

2. how to know where to find a B,C,D areas\neighborhoods in cities\ countries.3. how do I know if a property is worth the checking\ buying?

This will be reason #6272 of why I won’t buy in NJ 

BiggerPockets also has a calculator to analyze deals, and I highly recommend you start this as soon as possible, even if you are not ready to buy.

This is like buying any other property, it is valued at whatever the market is.  

Investment Info:Single-family residence buy & hold investment.

We said we would buy as-is and take care of all the trash ourselves.

Buy and Hold investing is a great avenue to begin with as most people live their lives off of residual income. 

My goal is to convert at least 1/4 of the units in a multifamily I buy into medium term furnished rentals (gradually) to bring in more cash flow.

So depending on what your investment goals are and what type of properties (Class A through C/D) and where in the city you want to buy, that can directly impact the level of stability one can find within the market here.