Questions about LG G3

I plan to get an LG G3 phone as my iPhone 5 is dying. I have read the specs of the new LG G3 on several sites and am confused. One spec sheet says the internal storage for data is 2GB while the other says it's 3GB. Which is correct? One spec sheet says the LG uses Gorilla Glass while another says it doesn't but Samsung does. The G3 has the speaker on the rear but won't it be covered when I purchase a case for the phone? Won't the sound get muffled by the case? Finally, regarding, the use of the micro SD cards; what exactly can be placed on the cards? I imagine photos can be stored on the cards? What else can be stored on the cards? The G3 got a very high rating.