For the usb cable, any good usb cable will be fine. Over time, you may want to replace your 751s with RR501 transceivers. The RR501 is "polite", it waits for the line to clear before sending the powerline signals while the 751 will just send them. If both of your 751s send at the same time, they will cancel both signals. Over time I replaced both 751s with 501s and got better service.
