Your images are distorted because the images sizes are set to fixed dimensions, both height and width, and if your images are not the same ratio they will appear distorted.
To remedy this situation, open your Admin and point your cursor to Configuration on the menu bar. Chose Images from the dropdown list and click on it. On this page is a list of the various image sizes, choose the image size you wish to edit and set one of the dimensions to 0. Make sure you also set the following two options: Calculate Image Size = true and Use Proportional Images on Products and Categories =1. This will alow your images to be resized according to their own proportions.