Best results if every source image has same width/height. That's the trick or make only 1 line of images with same height and then create a new content part and so on.
I think it would be cool thou if you had a new gallery component to add to the "articles" (like plain text...) And that would display a chosen image folder or something like that.
Good idea - but that makes sense with pre-sized images only. I have developed such function for other usage. Everey small gallery image is name like s_bababab.jpg and the click-zoom image is named x_bababab.jpg.
That is possible to do. Such function is easy to realize.