You mean like how I type on a 3.2" device while lying on my back? The keyboard on the iPad is much larger. I can type on my iPhone (or similar device) just fine. I don't see how that is going to be any worse on the iPad.
Your MBP is running an Intel Dual Core processor. The iPad is running a 1Ghz CPU made for this device. The first gen iPhone is small in comparison to the iPad. There was less surface area for the heat to be dissipated.
I don't put my current laptop on my lap. I use on for these:
http://www.ikea.com/us/en/catalog/products/80115790
So, the iPad will sit in the dock on this laptop cushion just like my Air is right now.
That would not be sweet, and I don't see what that has to do with the BT being crippled. You don't even need to use Bluetooth, there are remote mouse apps that work over WiFi right now. An App to do this could easily be created using WiFi.
Nice thought.