Gallery or Photos are both good, if a little different. (If you tenable picture backup, the pictures are backed up - the app has nothing to do with that.)
As far as a photo editing app, the best would be something like Paint.net on a PC or GIMP on Linux, Windows or MacOS. "Editing" apps on Android are mainly for making the picture look nicer - frames, silhouettes, tints, etc. There are no really good ones. Even Photoshop Express has only basic editing features.