Product with Options

Hi,

I have created a product with a few options fields including different characteristics. (by creating characteristics as indicated in your turorial and added them to a product and then defined as an option)

It all shows all right on my product page. My problem is: I have created 3 characteristics, say A is free B is 20€ and C 40€. If I select the option that has a cost it all goes fine. If I leave option A (free), it says the product is not available. In the manage variants on the option product, I have put the price to 0 in the fields.
How can I still have the possibliity not to pick any option that comes at cost? (before creating the characteristics it shows No and Yes + cost in the drop down list, all I want is to keep the possibility of having the No)

Second question:
Once I go to the checkout with all the options selected, they all appear as separate product in the cart but the main product is not at the top of the cart, how could I change the order the products are displayed in the cart?
On your demo website, the options show as a one product line with the details. How can this be set up?

Thank you very much for your help.

Indeed, spot on for both recommandations! Thank you Nicolas