Actually, I would have to disagree a bit. If I were starting again, I'd definitely use the Calfo style overflow, which you would not get on the "reef ready" tank. I do certainly agree that your tank should be drilled for a sump rather than using an external overflow. But, I think the Calfo set up is much better than the typical corner overflows.

As far as the sump goes, there are lots of choices, and you have all sorts of time to decide. Probably the best, but most expensive option, is to have a nice cast acrylic sump/refugium made to fit your stand. This can be designed in all sorts of ways. Another option is to modify a glass aquarium that fits in your stand by drilling it for an external pump, and adding some baffles/dividers for a refugium area and to help with the inevitable bubbles you get from the drain splashing down from the tank. A third option, the cheapest, is to use a plastic tub of sorts. It really can be as simple as something to hold the water from your tank and any equipment you want, like a skimmer, heaters, etc. Yu'll find all sorts of designs and ideas on line. One good place to look is in the DIY forum on reefcentral.

As far as plumbing, the basic scenario is: water drains from your tank via an overflow of sorts, falls down into the sump where it collects, then you pump it back up to the tank. Use a good external pump for your main circulation; it will stay cleaner, hold its flow better, and transfer less heat to the tank than a submersible. Plan on adding flow in the main tank via a closed loop or powerheads. These can be cheap (maxijets) or expensive and nice. (tunze) A closed loop is simply a drain from the tank, submerged, that leads to an external pump, which then recirculates the water back into the tank, typically through multiple outlets. My closed loop pushes water through 2 sea-swirls, which do a good job of moving the current around. Recently there's a device called "ocean motion" (There's a thread on this in the vendor/product experience forum) which basically rotates current through either 4 or 8 outlets. It seems to be a good device which gives you all sorts of options for providing variable currents in your tank.