Question What can i do for more battery life?

Hello,

What can i do for more battery life?
Is 2000 mAh battery enough to increase battery backup for "Galaxy Core i8262"?
How many hours do you think i'll get with 2000 mAh if i watch video's and browse the web?
From which company do you suggest me to purchase a battery for "Galaxy Core i8262"?
How much is the maximum amount of mAh battery which i can add to my "Galaxy Core i8262"?
What happens when i add large battery more than 5000+ mAh??

Please advice.

Thank you!