No they will not test for the sex of the donor. You can freeze the urine, and I have heard that I can last for a year. Concern is always bacteria that grows within the urine which at that point the tester will be able to tell that you substituted. If you are going to substitute, synthetic urine is the best way to go. I personally use Quick Fix-it comes with the bottle that has a temp strip on it and a little heating pad. Shelf life is 2 years and they will replace for free once it is expired. You can heat it up as many times as you want and not have to worry about bacteria.

Hope this helps