In the book for which this series is based, David had an African American boyfriend, and Andrew wasn't as desperate and needy to be his only boyfriend as shown here. Although, of course, Andrew did have extreme control issues... his jealousy, as shown in the series, stemmed from his two best friends, David and Jeffrey, becoming close, and living close in another state, and didn't seem to need him any longer.
The exterior shots of David Madson's apartment is the Binford Lofts in the Arts District of Downtown Los Angeles, which was also used as the primary residence in New Girl (2011).
Though it sounds like David's dog is named Prince, the dog's name was Prints.