Ladybasenji, where are you in Quebec? Montreal? We have a place in Gatineau (Aylmer sector) and one of my dogs might even be related to yours. You're experiences with your girl remind me so much of my first basenji, about 20 years ago–it gets easier, I swear! Let me know if you'd like help with Lady--they're nothing like labs and will never be "obedient" but there are tricks for training them : D
You can find a lot of puppy collars at thrift shops for pretty cheap - would never pay full price for one. I'm getting mine at 14 weeks and was told that 8-12 inches was what was being used - then at 4- 6 months graduate to 10-14 inch collar.
A lot of research shows that dogs develop male hormone driven behavior well before a year, and that neutering after the behavior will not stop them. But the decrease in hormones will help making training those behaviors far easier, so early or late, you can usually get a bump in decreasing unwanted behaviors.
Glad all is well.