Can I transfer photos from my camera to my iPad3 just by buying the Camera Connection Kit; do I need to buy an additional App to the built-in photo editing one?
You do not need and additional app for transferring. If you have iCloud with Photo Stream turned on you can then synch your photos among all of your "i" devices.
" After you make the connection, your iPad automatically opens the Photos app, which lets you choose which photos and videos to import, then organizes them into albums. When you sync iPad to your PC or Mac, the photos and videos on your iPad are added to your computer's photo library.
iPad and the Camera Connection Kit support standard photo formats, including JPEG and RAW, along with SD and HD video formats, including H.264 and MPEG-4."