The mAh is milli ampere hour, a unit of electric charge. Follow the link below for a short explanation:

http://whatis.techtarget.com/definition/0,,sid9_gci214359,00.html

As for battery life, here are sites that talk about ways to take care of your battery, plus the fact that Li-ion batteries do not suffer from memory effect:

http://www.friedbeef.com/top-15-ways-to-extend-your-laptop-battery-life/
http://www.wisegeek.com/what-is-a-li...on-battery.htm

Here's another site that has a different take on memory effect:

http://www.dansdata.com/gz011.htm

Eventually, you have to decide which point of view is correct. Or look for a more credible info source.