Bottom card drawn during epidemic: Are 3 cubes added to the city pictured, when the disease in that city's region has already been eradicated?
Further clarification isn't needed. Under the Eradicating a Disease section you quoted (emphasis mine), the rules instruct you to put the cubes away, they will not be used for the rest of the game.


  If a cure for a given disease has been discovered and all of the disease cubes of that color have been removed from the board, ﬂip the Cure marker for the disease to the “Sunset” side. From now on, cards of this color have no eﬀect when drawn on the Infector’s turn. Take all of the cubes of the eradicated color and place them back in the box—they will not be used again for the rest of the game.


The only exception to this rule would be from the Pandemic: On the Brink expansion Virulent Strain card Hidden Pocket, where it is possible for a disease that has been eradicated to come back.