The reason I asked her age is that some caches are specifically designed for kids and are easier hides with contents that kids will enjoy. As an adult, I really enjoy the caches that contain geocoins or travel bugs (all explained on geocaching.com).
As for battery life, that is one of the reasons I picked this GPS. When it is plugged in to the computer it doesn’t use the battery and this is also true if you have a car charger. So I use regular batteries and when I am in the car or at the computer it doesn’t use up any of the battery life. I can geocache fairly consistently for about a week (that is 5 or 6 forays of about 2–3 hours each) on one set of batteries.
The other benefit of this GPS unit is that you can get a memory card of any size you desire and keep records of available caches (I typically download about 500 caches at a time to my unit but I have a larger memory card with all my topo maps for search and rescue).