Yes, Gionee A1 Lite does support OTG.
Gionee A1 Lite has a metal Alluminimum Alloy body.
No. Gionee A1 Lite is not a waterproof phone. But it is made of Aluminium Alloy and hence you may get some protection against damage.
Yes, Gionee A1 Lite has 2 dedicated sim card slots and 1 dedicated memory card slot. So, you can use all of them at one go.