Install and modify a carousel for WP (or similar)

Hello. I have a client who is an artist. She has a website with a gallery. She wants a carousel on the frontpage where she can post new images through a backend, for example Wordpress. The user wants to upload images in different sizes, but most will be around 700px width. Max-size in both width and height has to be 700px, if the user goes above that with an upload, it has to scale the picture down so that it has a max-size of 700px either direction. The image also has to be scaled down proportionally of course. So if she uploads a picture that is 200 x 650px it will stay that way, but if she uploads one that is 1400x1400px it will be scaled down to 700x700px etc. No "fake" height with whitespace to make the image scale to a fixed height, auto height as seen in this example is what we are looking for: [login to view URL] It should be possible to change the max-width from 700px through the backend if it ever needs to change. It doesn't really matter what carousel you use as long as it is responsive, bug free and without watermarks. It also has to be simple for the user to upload pictures. So you have to: Install a carousel, modify it to suit these needs and implement it with Wordpress or a similar SIMPLE backend which she can post from - there's tons of WP carousels out there already though, so it should be pretty easy. You will be provided with SQL passwords, FTP, a pre-install of Wordpress if needed and everything else needed of course.