Hi there Alexandra!
Regarding the changing of shapes you have several options:
-Option 1: Since these are pretty simple shapes you can achieve the same result using only CSS and divs instead of using SVG, and then you can modify the border-radius property of each element.
-Option 2: If you want to use SVG to handle the shape change MorphSVG plugin is your best option,
-Option 3: You can always alter the path directly too targeting the d attribute, but it won't look as smooth and you'll need to make sure that all of your SVG paths have the same number of nodes.
Hope that helps!