Ebb And Gro System... Now What?

So I just bought a used ebb and gro system. The controller bucket and pumps work great. I don't have any buckets though so I need to figure out how I want to run this system. I'm thinking about making some diy 5 gallon ebb and flow buckets. all with air stones for good measure. I don't want a very long veg all plants will be coming in as rather mature clones.

the setup:
3 x DE HPS
each light has 4ft x 6ft x 12ft grow area
temp and humidity controlled
hepa and carbon filtered air

Do you think I can get away with just 6 5 gallon buckets per light 18 in total?
Also I'm considering running this system more like a RDWC instead of ebb and gro. So I will flood the pots and leave them flooded for maybe 12 hours then drain and fill back up. Is there any sense in this at all?
The control bucket has .5" hose do I need to upgrade that to 1+"?

Thanks for your comments.