its a good idea a phone cradel on the bike i think despite comments from other people. I know when i was riding to meet up with someone to catch a train somewhere, i needed to use my phone to contact them on the trip without stopping. The cradel would be a great idea, but not to be used to regulary on rides. It depends where your riding aswell, if it will distract you or not. On a busy road not good, but on smaller streets better.

In answer to your questions:
-definatley water proof
- i'm not sure about the recharger though, i dont think you will be using the phone for that much time that it would need a recharge, hopefully not anyway.

What would the cradel look like, keeping in mind all phones are different shapes and sizes, how will it be attached.

Any photos, drawing or diagrams would be great if this goes ahead!

Hope this Helps