one collection (if the sperm shows good motility - "life"), should have anywhere from 2-5 breedings worth, depending on the size of the dog.
I think it can get expensive for when the bitch comes in, and testing her for the "right" time to best insert the straws.
And no, the dog does not have to be alive to collect, as there is sperm always waiting in the dog, so as long as he had not just been bred before death, it might be worth collecting if the dog is newly deceased