Answer to "Has anyone attempted to separate LCD from Glass Digitizer?"You can use an optical glue for securing. It's similar to what your dentist uses. Once applied you use a UV light to cure it. It's incredibly expensive and I only suggest using it on expensive LCD/Digitizers such as Samsung phones and iPhone 5.
Answer to "Can I use the earpiece from iPhone 4 to iPhone 4S?"No the speaker may work however the sensors don't line up.