nice tank! Well, remember to quarantine any new fish for 2 weeks. Trust me...it'll save you trouble! You could divide.... But you'll need TONS of plants, especially for the sorority. Females and Males can detect each other because of smell.... they give off pheromones of "I'm here" and "I'm sick" and such

You can make your own, or buy your own. THIS is the one I have for a 10 gallon
http://www.ebay.ca/itm/Lees-AQ2-Aqua...item256344a1b4 and I like it. turdy, flexible and clamps nicely to the sides of the tank without worrying of the hood sitting wonky!
If the tank divider sits about 3 or more inches above the water yes they can be reliable. Take in mind your own fish.... My females, 4 jump so far - and 2 can jump over 4 inches! I also have an aggressive female, and a new aggressive female both of which need to be divided anyways xD
And I know. I had 4 in a 29 long

it looked so bare.... xD I have a 40 for them soon. Imagine how bad THAT will be x.x