Arowanas might not be the best choice for the footprint of tank, but the rest should be fine. I guess you can make it work though.
As far as cleaning the sand, its alot easier than with gravel. For one, the uneaten food, bacteria, and feces dont hide under it as they do with gravel. Its just a matter of pointing out where the feces and everything else is and vacuuming it up. Theres no need to dig you gravel vac into the sand as nothing will be under there. Stir up the sand every once in a while as sometimes toxins accumulate under it.
Another advantage with sand is that if you have good filtration and bottom fish sometimes they will kick up the feces and the filter will just suck it right up!