"hurt" hands ... I used to get that ... Now I only get that if I'm marathon typing.
OK, you get the "hurt hands" (or more specifically in fingers or joints or writs) because of the unnatural way in which you're typing. Hands are not meant to be straight in line the way that a notebook forces you to have them. I have an external keyboard which I plug in when typing at the desk; when full on mobile, I pause frequently. I suffer from RSI's, so it's important to do the "rest thing" even when the mojo's going.
Auto save - mostly what ZM said (other versions of Word do it slightly differently, but that's the basic way of it.)
Backup - if you are not doing this religiously (in one [or more] of many different ways) you are playing dice with your soul. Physical backup to a Disk, USB stick, external Hard Drive, or Cloud service ... pick one, do it religiously, then pick another, and do it religiously, too.
Battery Life: the "more" you use it, the faster the drain. The "minutes left" thing is an approximation (Windows is not as accurate with that as it could be). If you are using your CD or playing audio a lot while typing, you are draining the battery faster. The "7 hours battery life" could be what the state as "mild usage" (this includes times where it goes into battery save mode and active modes; 8 hours is norm, longer time exists for other hardware.) There would also be another benchmark of extreme usage (4 hours is the norm.)
Note: Also check your hardware settings for the computer's battery usage. If your computer is inactive for (say 15 minutes), have the computer start using battery saving settings. It's been a while since I used Windows, but this should be in the Control Panel under "power settings" or "energy saver" or something along that line...