Okay, first, get the pet insurance. If this puppy has an issue, insurance can pay for itself. A friend imported a chow pup from show breeders. The rest of the litter (most also here in US) are great. Her vet bills in 2 years were over $20,000 and her insurance paid nearly every bit of it.
Then, give it a couple of months at least, then perhaps consider Penn Hip. I prefer OFA, but if your pups hips are that lax at this point, Penn Hip can be done at 16 wks. I personally would wait til 6 mos and get a vet who is very experienced in OFA to check the hips.
In the meantime, please check your contract with the breeder to see if there is a refund, help with surgery or what in case of genetic issues. Get the sire and dam's names and/or AKC reg numbers and go check to see if the parents are tested, previous pup, other dogs from the kennel. No matter how much you like a breeder, see the results on the official pages for yourself. A responsible breeder is proud of you seeing all they have done.
Finally, some bit a caution. Basenji people tend to be nonchalant about umbilical hernias. First, if they are small, they do appear to "close off." In reality, many vets feel that the opening is still there, just tiny enough to seem closed. Read up some, then make a decision on whether you want it surgically closed just in case. My own bias, no fact to support it, is that if it's that small, it's never going to be a problem. But you should be aware. The other issue is that while most are small, if your pup's doesn't get smaller, gets larger, bulges...that can be anything from a medical concern to life and death emergency. If it is large enough, some of the intestines can slide through, get trapped, and cut off blood flow. So if it is small, don't fixate, but please keep an eye on it.