Desktop to iPad is simple as long as your iPad is connected to the internet, just select: [Route] | [Save to Cloud] on the PC and open from cloud on the iPad using [Route] | [Open from Cloud].
To get your route onto a non SkyDemon GPS you need to either use a USB cable or plug the SD card into your PC.
I generally fly with a cheapy GPS unit, but also take an iPad with an external GPS as a backup