The longer and more often you look at the LCD screen. The shorter the battery life. Do you use LiveView instead of the viewfinder.... the worse the battery life. After a few pictures you know your exposure and should only need to check after a few dozen pictures. I don't pick and delete my images with the camera (kills battery life and can't see sharpness on a tiny screen), but copy the images to my computer to delete them.
A grip is an attachment that fits the bottom of your DSLR that makes it easier to hold your camera for portrait photography (camera on it's side). It allows you to hold one or two additional batteries. It is also an AA battery adapter. Do you have big hands, it may make your camera easier to hold. Just realized your entry Nikon does not have an official grip. There are third party grips, but can't recommend them without experience.
Camera is perfectly secure with a photographer backpack. You just adjust the padding for bigger and smaller camera/lenses. You need to think....
- do you just want a backpack to hold your camera? What about something bigger for lenses? flash? spare batteries? spare media card? food? drinks? valuables? a camcorder? tablet? laptop? Pay attention to weight!
- do you want something that holds a lot? do you want something that can fit as airline carry-on?
- rain protection? I like LowePro?
- access? back? side? mid?
- theft? Do you want something that looks like a camera bag? Or something that blends in as a regular backpack when travelling on public transit?
My fav backpack...
http://store.lowepro.com/ca/backpacks/rover-aw-ii-ca
My second fav backpack when travelling with longer lenses and needing a clean place to open up.
http://store.lowepro.com/ca/backpacks/flipside-400-aw-ca
When I need to carry a second mounted DSLR and I can use my car...
http://www.tamrac.com/products/cyberproexpress/
