Are they installing the front plate on all new deliveries now? From pics I have seen it appears so. If so, anyone know if they are screwed on or taped?
To answer your questions...
Automatic installation of front plate mount probably depends upon the delivery center and/or the tech handling your car. As was mentioned upthread, it doesn't hurt to call the delivery center and request that they not install it. As CA is a required front plate state, you might be told that they have to install it.
If they do, it's mounted with double-sided tape so after you drive it off the lot, get some dental floss (and optionally, a heat gun / hair dryer) and go at it.
Before picking up my car last year I asked the agent (in Las Vegas) to relay my request to the Fremont, CA center to not install the mount. She told me that they have to according to CA DMV laws. When I got to the delivery center, none of the cars in the lot had them on. So YMMV.