RE: Electric setup for Paris White DC-3
MotoCalc is a good place to start. Be sure to disable the brushless motor heat compensation as this usually causes the results to look poor. It is much more accurate with this option disabled.
On brushless motors, use one ESC per motor. On brushed motors, you can use either one ESC per motor or multiple motors per ESC.
For an example of the power system, check out this link to the [link=http://www.hobby-lobby.com/taxicup.htm]Graupner Taxi Cup II[/link] at Hobby Lobby. See the size plane that it flies and then compare to twice the power system on your application.