Here are some threads on skimmers that you might find helpful
http://www.reeffrontiers.com/forums/showthread.php?t=39686
http://www.reeffrontiers.com/forums/showthread.php?t=39674
The second one was moved from a different forum as it got off topic of the original thread so ignore how it starts as some of the first posts are in reference to everything that went on before it was moved. Both of these threads have some good discussion on different aspects of skimmers, what the number ratings mean and how they correlate to your needs. Both of these threads have a lot of input from our resident skimmer experts, luke33 and skimerwhisperer and if you post a question on either thread you will likely get one or both of them to chime in with an opinion.
IMO the skimmer is your most important piece of equipment, buy the best you can. Inadequate skimming can lead to problems which are frustrating and require a lot of work to take care of (algae, high nitrates=extra water changes, siphoning off/scrubbing rocks and sand) and results in many a new reef keeper getting frustrated and quitting). The high end is many of the German made brands (e.g. Bubble King and H&S) and the cone skimmers, there are also a couple of good knock off brands, Octopus and MSX that I hear are worth looking at.
Flow is very important as many have mentioned, different coral have different requirements, but it is also important in a FOWLR in order to keep detrius(sp?)-uneaten food and fish poop-in suspension until it can be picked up by your overflows and taken to the sump and skimmer for removal. I would suggest looking into the gyre theory for flow in your tank, I heard Jake Adams speak at our local club meeting in November and wish I had known about it before I set up my new tank, I would have made some different decisions on my closed loop set-up if I had, although I have been able to adapt my setup to obtaine a gyre.
I would also suggest looking into the members showcase forum, you will find many tank build projects there, that can help you see how others have set up their tanks. There are many different ways and many different opinions so in the end it is up to you to make the best decisions for you.
I do not recall if you mentioned whether you have a reef ready tank (built in overflows) they can give you much better flood protection than having to do an hang on back overflow. With built in overflow, with back-up drains, siphon breaks on your return lines and plenty of extra room in your sump (to allow room for the water that will drain in a power outage) you will not have to worry much about flooding.
I like that you are doing a lot of research, like I said there are many options, and even more opinions in this hobby (both which make it more difficult for the newbie), but I have always had the desire to understand first before I do something. To me it has to make sense before I change/do something.
Thanks.
