When Omar comes back to the abandoned home he's living in; after he looks around to be sure it's safe; he throws a wall switch to turn on the lights. Since this is an abandoned home it wouldn't have electricity turned on; and wall switches wouldn't work. And since it's marked by the city with a phone number to call for trapped animals; we know it's abandoned. In the other case with people living in abandoned homes electricity was being brought in by extension cords. Since all the meters are removed from homes like these there would be no other way to get electricity into the house.
At the half, Avon's team is up 45-33, and their score is marked in red, as the Visitors. At the end of the game, when his team loses, they're the Home team, with 75, while the Visitors are shown with 77 (then 79 on the last basket).
In Season 1, Avon Barksdale and Stringer Bell's corporation is referred to as D&B Enterprises. In later seasons, the corporation is given as B&B Enterprises. There is no indication that the characters changed the name of their company.