Tidying up a wordpress wp-eCommerce site

Hi

I have put together a site using wp-eCommerce and a theme from Storefront Themes.

There are a number of general tidying up things that I need to do for the site. Have a look at the site at velo26.com

1 – On the main menu at the top, I would like to make the left most button align with the edge of the menu, instead of being a handful of pixels in. Likewise I want the right most button to align with the right hand side of the menu.

2 – I would like to smarten up the three text widgets at the bottom of the page, Paiement Sécurisé
, Contactez Nous and Livraison. For the payment one I would like some little images for the different types of payment. For the contact one, I would like some little icons for the phone and email and address. And for the delivery one I want the icons for the delivery from the relevant colissimo and chronopost sites.

3 – When you go to the products page, the price after 'Ancien Prix' is not aligned with the price below it for 'Prix' I would like them lined up.

4 – If you add something to your panier and then go to have a look at it the page that comes up is not great. I would like to have some more definition between the 'Identifiez-vous' section and the 'Inscrivez-vous dès maintenant' section. And have both sections tidied up a bit. i.e. have the login button so it lines up with the two boxes above it. Sort out the way the text flows around the email box, etc.

I would like it if these changes can be made with custom css files or something, in such a way that updating the theme can be done without it removing all the changes. Or if not, then I would like clear code and instructions to be able to make the same modifications to future upgrades of the theme.