Most RAM manufacturers have some sort of memory finder tool on their website that helps you find the correct RAM for your computer. For instance:
I can't seem to find your particular model on Corsair's site, but Crucial gives the following result:
http://www.crucial.com/store/listparts.aspx?model=Pavilion%20g4-1164ca&Cat=RAM
According to Crucial, your laptop supports DDR3-1333 (PC3-10600) and DDR3-1600 (PC3-12800) RAM. The Corsair Vengeance RAM you linked to is DDR3-1600, so should work fine in your laptop.
As for battery life - going from 4 GB to 8 GB is going to have a slight impact on battery life. Also, higher-performance RAM usually requires higher voltage, which also negatively affects battery life. The Corsair Vengeance RAM you linked to runs at 1.5 V, whereas this Crucial RAM runs at 1.35 V, not to mention is significantly cheaper.