IPhone – How do iPhones acquire date and time

The comparable page you're looking for is: http://www.apple.com/ipad/LTE/. A1454 is used for AT&T and similar Canadian networks only, while Sprint, Verizon and overseas carriers use A1455.

All bands are also listed on the specs page:

• Model A1454
  • GSM/EDGE (850, 900, 1800, 1900 MHz)
  • UMTS/HSPA+/DC-HSDPA (850, 900, 1900, 2100 MHz)
  • LTE (Bands 4 and 17)
• Model A1455
  • CDMA EV-DO Rev. A and Rev. B (800, 1900, 2100 MHz)
  • GSM/EDGE (850, 900, 1800, 1900 MHz)
  • UMTS/HSPA+/DC-HSDPA (850, 900, 1900, 2100 MHz)
  • LTE (Bands 1, 3, 5, 13, 25)

Yes. The wattage ratings are maximum and all iOS devices will only pull the current they need to charge.

Should a device or an adapter get too hot to operate safely, they will shut off.