Dogs are all about the same....they will breed as long as the female is in standing heat. The male should not be allowed to be roaming freely with the female...or she may end up attacking the male...when he becomes annoying. As far as percentages of being pregnant? It depends on timing of ovulation, and the sperm count of the male, health and age of both dogs, etc.
If you are planning on breeding and asking these questions....then please don't. You are not educated enough.