Well we want to transmit HD video any solutions for that ?
Not CHDK, that's for sure. There are many off the shelf solutions for wireless video, and most of them are smaller and lower power than anything you could hack into a P&S camera. I'd suggest searching for RC related forums, a lot of people have done this in various forms.
If you also wanted to take relatively high quality stills while flying, CHDK might be of some use.
