Personally, if I were to go with a frag tank I would use at least a 20 long tank. With investing in lights it shouldn't be much of cost increase to go up 1 size tank and it will allow you to grow tons more corals than a 10g will.
As for flow, I was planning on using a water pump or canister filter to move water in the tank. You can put the intake at one end of the tank with the outlet at the other so it is constantly moving water across the entire tank. I was also going to use a powerhead or 2 to create higher flow for certain corals.
If it's alive bleach will kill it. I would use a 1 part bleach to 9 parts water dillution to clean the tank. Let it soak for a day or so then rinse it out. As long as there is no bleach smell left it is safe.