Hi guys , how are you!!

I just bought a Walkera 53Q Metal Edition Heli and was wondering if I can buy a bigger battery for a longer flight time.
I'm new at this , so can I go from the 7.4V 1200mAh Li-Po battery to a 7.4V 3000mAh or bigger battery??
Do I need to get a bigger battery charger for a bigger battery??

I'm also wondering if I should get a balancer , and what would be a good one for my Heli??

Thanks in advance

This is the Heli for more info
http://www.nitroplanes.com/20wahm2cnupr.html