Can I overcharge the Mogul? Possible to turn screen off while plugged in?

[tracerit]

I charge the phone through a docking cradle that I picked up from ebay and I have two questions:

1. Once the phone is fully charged and still connected to the USB cradle, does it continue to charge? Is this bad?

2. Is there any way to turn the screen off automatically while being connected to the USB cable? Much like how the screen just timeouts with no use.