[Micah]

The answer to your second question is because the scouting reports aren't completely accurate. The number of indies doesn't change, your scouting report does. If it's going from 30-80 troops over a few turns there are probably about 50 guys there. If you keep track of it from turn to turn you'll get a good idea of the true strength as you gather intelligence, otherwise you're relying on a small amount of time, so you shouldn't be completely sure what you're going up against, it's one of the judgement calls you have to make.