can you anwser my questions??

i like having the return slow, the refugium works better with lower flow anyway, and boost the current in the tank with powerheads. by breaking it up you get more flexibility in directing your flow, (more flow at the bottom where it is most useful for keeping debris in suspension), and you can sleep a little better at night. I had a drain clog once though and it caused a good deal of flooding so I may be a little gun shy with high rate returns.

+1 to bio balls being outdated. you need denitrification more than aerobic filtration...your rock, sand and decor will provide plenty of surface area for aerobic filtration

 

As for an overflow, I use a Eshopps 800 and a Rio 2100 return, I think that combo works really well. By the way, I also have a 55. As for lighting, as already mentioned, I would get at least a 4 x54 T5 setup, you will be able to keep softies and many lps. I didn't read anything about any rock? Are you planning on using live rock as the biological filtration?