For me megapixel equates the more megapixels the bigger picture you can print. A 3 megapixel will print a pretty good quality 8 X 11. Since I don't have anything to print bigger with, I'm not in a hurry to upgrade to a higher megapixel camera, although I've been told a 5 mp Camera could print a better copy of a 8 x 11 print.
Edit to add: For putting pics on the web you could easily get by with 1 megapixel, if they still sell them that low.
I've had two digital cameras. One had a rechargable battery, my current one uses 2 AA batteries. I prefer the AA's since they are readily available everywhere.