Bs are very special dogs. It is really good you are doing research as basenjis are often gotten by people who think they will be as trainable as a german shepherd or take abuse from little kids like a golden retriever or can get by with a little ten minute walk a day– not!
I've had basenjis for 39 years, and breeders are not all the same. Search out breeders who are known for the reliable temperment of their dogs.
Older cats? A puppy is going to want to play with, jump on and mouth the kitties. The cats are going to need places where they can get away and look down on the little beastie.
I brought home a new puppy in 1998 when my Aby cats were 3 & 4 and ended up putting a cat tree in every room that did not already have a high piece of furniture as Belle "just wanted to play." They had grown up with another basenji, Binta, who was about 8 when they came to live with us and she never chased them and basically ignored them. So to all the sudden have a puppy after them constantly was a real stressor and one cat, Zaki started overgrooming and licked his stomach raw. We always crated Belle at night so the cats could feel safe sleeping with us, yet Belle could be in the same room with us. Worked well for 11 years.
Basenjis are really magical beings... can't imagine having another kind of dog.