Hi,
Having a characteristic which changes the main image of the product is possible with HikaShop and the characteristics data, including the prices, can be imported (you can export a product data with the "export" button of the products listing on your website in order to get a CSV example of what to do for the CSV to import).
And you can have a radio selection with the image as well if you configure your characteristic with the img tag for each color value and set the "radio" characteristic display method in the configuration.
Regarding the tooltip which displays on the images of the characteristic, I guess that you could add tooltip tags in the values of the characteristic in order to manage it. But you'll be limited to 256 characters for each value, so it won't be enough to have everything fit in it, so it might require some custom development.