that galaxy a3 does not support OTG.

if you are charging the phone with wireless charger, that's "normal".But if you are charging it whit a normal charger maybe that's the problem. Try with another charger.But if the problem still happening try to turn on the fast charging mode in setti...

what do you mean?

I live in Colombia and I have already android nougat... check the software update

that depends of where do you live. I guess that it will come soon but it'll be available first in different zones.