Selecting pumps for flow is very subjective. You need to balance what your trying to do with the system against the available equipment and your budget. There is no "one size fits all" here. For esample, you could go out and get a couple of EcoTech Marine VorTech pumps. You'd get great variable flow, battery backup and all that. However, the cost would be about $600 to about $750 depending upon options. At the extreme other end you could get a pair of Marineland Maxi-Jet Pro powerheads for about $55. However these pumps can't come close to what the VorTech pumps can do. As for something in between these extremes, I like Hydor and JBL, but there are plenty of other good ones out there.
Considering what you seem to have in the tank, I'd recommend you opt for something toward the less expensive side. If later on you decide you want something a lot better, you don't have a lot invested in the less expensive pumps.
As for pump placement, this is more a trial and error process. You want to make the pumps as unobtrusive as possible and still give you good flow. All that live rock is going to channel water differently. I'd start with the pumps more or less in the middle of each side and move them around and adjust their direction until you get the flow you want, and no dead spots. With inexpensive pumps you can always add one or two more if you really need it. Once you have them placed, don't be afraid to move them if you see dirt accumulating someplace or you get new corals.