HP should be a reasonable brand although I've not used them myself.
Battery life will decrease over time and will vary depending on the laptop spec. In general a higher performance laptop (larger screen, dedicated gpu, faster cpu) will have a shorter battery life. Lower powered laptops and notebooks/ultrabooks should have a longer battery life. I'd generally expect between 3 and 8 hours of life between charges when new, after a couple of years that could have halved (or worse).
Make sure the hard drive is large enough for what you're likely to want to store on it and still have a good margin of space free. The performance will significantly decrease if you've got less than 20% of the drive space free.
Personally I'd also work on the principle of replacing a laptop every 3-5 years. If you get longer out of it then that's a bonus but getting 10 years out of a laptop (especially if you're buying at the low end of the market) is unlikely to happen.