Ram Upgrade Help!

Hello guys, I am the happy owner of a 2012 macbook pro 2.3 Ghx i7 with 4Gb of ram. I have tinkering with the idea of upgrading to 16Gb over the holidays =). I was wondering if you could explain a few things to me.
First, does my machine support 16Gb altough apple claims to support maximum 8Gb? Secondly, what is the difference between 1.5 and 1.35 V ram, will 1.5V work in my machine, will it lower my battery life when in use (I am a student so battery life is pretty important to me). Lastly, will I void my warranty by switching ram my self, should I save the module in case my computer ****s up and I need to return it to apple (ie. switch out my ram and put the stock ram back in).

Thank You,
Martin Krastev