Making basement deeper in Baltimore City

[Erick Chavarria]

I have a rental property that would benefit from an additional bedroom. The basement is currently 6'3" high. How complicated is it to dig another 12-18 inches in a section of the basement to be able to build a 3rd legal bedroom? The basement already has a back door plus two large windows.

Do I need to get a permit? 

Do I need to hire an Engineer or is this something a contractor can easily do without much complication? 

Basement doesn't have a sump pump, do I need to put one in? 

Thanks in advance for you help!