I have profiles for 2 specific cameras I use. Although I've read the Lab notes for PE I'm still uncertain whether I can set up LR to apply the correct profile to the specific camera. Is that option automatic when I use the procedure for setting up the default profile? Or do I need to use the option in Preferences that relate to specific camera registration number?
If you have 2 cameras of the same model number and you wish to have two different camera "defaults", yes, you must have the Camera Raw preferences set to apply the defaults based on the camera serial number. If you have two different models of the same brand, you don't need to worry about the serial number preference.