Yes, Panasonic Eluga A3 is a metal body phone.
Eluga A3 does have 3GB LPDDR3 RAM.
Panasonic Eluga A3 does come with Fast charger. To get the fast charging, you need to use the company provided charger.
Yes, Eluga A3 does have a gyroscope sensor.
You can use one micro and one nano sized sim card in Eluga A3.