Regarding your battery
Here's my opinion on your battery.
The original battery inside your phone now is 1340mAh (milliamp hours).
The one you're looking at is 2100mAh, which for you would be a 56.71% increase in battery life.
Ridiculous battery life
1970's soviet era technology backing for your phone (it's terrible looking).
No accessories skins/acrylics would really accommodate your phone. You'd have to rely on a universal-type side holster.
The battery is off-brand and ships from China, the quality of these cells are unknown, and who knows how old.
Perhaps try reputable battery brands such as "Seidio" or "Mugen"
I recently purchased a Seidio 1500mAh slim profile battery, which gives me an 11.94% increase in power, whilst allowing me to keep my current backing on with NO increase in device thickness.
Couple this with some operating system tweaks and or a new rom specifically made for battery improvements and you should really enjoy from then on in.