presentation of images in product list

Hi,

First you want to turn off the "force size" setting and you want to specify a height but no width in the thumbnails size setting of your menu item.
That way, each image will have the same height, but it width will vary based on the ratio of the image, like you need them to be.
However, each row will still have the same number of products. To change that, you'll have to add custom CSS in order to have them arrange dynamically like you need them.
With the appropriate custom CSS, you should be able to do what you have in your first screenshot.
However, with just the options, it's not possible.

Hi,

Well, I don't know excatly. It would require some proper testing. A web designer knowing well CSS will probably spend one or even several hours to be able to write the proper CSS while testing things out.
It's not just one or two simple lines I could provide off the top of my head.

Hi,

You could but it will be more complex as you'll have to rewrite PHP, add the javascript library and integrate it to the page, and maybe tweak the CSS to adapt that library default display to your needs.
So I would still recommend to go with just the CSS customizations like I was saying before.