English Bulldog and American Bulldog crosses are somewhere in the 50-100 pound range; hybrids vary so much in terms of size that the best way to estimate how large yours may grow is to see the parents. EngAms often are larger, more athletic looking and with a more proportionate body than the English but usually retain the broad wrinkled head and strong chest. The short, low maintenance coat is usually multicolored (including white).
This breed is not one of the easiest to train. That being said, if from the beginning you can consistently instruct them with patience (and offer them plenty of treats and praise), results will gradually come; often they are said to be stubborn. Note the EngAm should have early socialization to not be overly assertive with other pets if they inherit more American Bulldog characteristics.
While many tend to be skeptical of bulldog breeds, if raised with love and patience, they are good family companions. They enjoy playing, attention, and affection which children provide so well, however, their large size may pose an accidental hazard to very small children. Most will do fine with other pets if socialized from a young age. Although watchful and protective, they are not outright aggressive and make good watch dogs. In fact, they will often be friendly and outgoing-- although sometimes remaining reserved until familiar with the person.
Although more athletic than the purebred English, they (on average) need only a medium amount of activity. At least 30 minutes per day of walks and outdoor playtime is recommended. A fenced yard is also highly desirable for this hybrid. EngAms also enjoy trips to the dog park and plenty of toys!