thanks fullleatherjacket did not want to make that mistale.
That's OK, but please do read the full P40C manual before you plan any further.
http://www.action-electronics.co.uk/pdfs/P40C.pdfYou
may need a separate battery for each motor but you will certainly need a separate supply for the receiver. If your ESCs have BEC then this must be disabled in BOTH units, and there are certain makes of ESC which have proven not to like working properly with any type of mixer. PM me for details to see if those you have planned to use are on the list!
If you don't already have two suitable ESCs then P94 is a better buy (apart from being a more versatile and compact unit), being cheaper than two x 20A ESCs and a mixer when bought together. You can knock approx 15% off the published UK prices for US exports too, so a P94 will cost around $110US built, tested and shipped.
FLJ