They have their own strengths and weaknesses as warriors. I wouldn't say one culture inherently produces better warriors than the other. Traditionally Redguards are a more agile warrior, while Nords are heavier soldiers, but there's plenty of room for diversity in each culture. That's just the general trend.
As far as the provinces go, it really depends on which race is currently more united. Like you say, the Redguards were beat in the past because they were divided and couldn't unite against the Nords. Do take note though that the situation has reversed itself in the most recent TES game. The Redguards are now united while the Nords fight amongst themselves. If they were to duke it out now, Hammerfell would surely defeat Skyrim.
Oh, and you probably should have just made a single thread for your questions. Making multiple threads for your questions is generally frowned upon. But I see you're new here, so we'll let this one go.