Q: How long does the battery last (from a full charge to no power at all)? Does leaving it on charge the whole time damage it in any way?
A: it will depend on your usage but 3-4 hours I have always used my laptops unplugged and only powered them when needed and I have never had one go dead on me in 7 years Lithium-ion battery are supposed to be better than older battery type on not going bad but I would not leave one plugged in all the time unless you want a dead battery also with the magsafe connector that seems to become damaged with use (mine lasted 7 months before needing changing) only plugging it in when needed seems like a good idea to me