If you like your friends site layout, your friend would be a great place to start. This would give you immediate feedback and any questions that you would have alter without waiting. But here is what I can comment on.
For #1, go to admin-configuration-product listing and turn on the add to cart button. There are many settings for add to cart, which you want the one to display the cart button.
For #2, you will have to modify the core file. You have to take away the core functionality of keeping the description on 1 line. Very easy to do, but code not in front of me at the moment. This is mainly why I said above to ask your friend as since he already done it, he can advise you on what changes he did. But the file would be in modules/product_listing.php. Just make a backup before you edit so you can revert back in case you make errors.
For #3, it looks like it is using the Tabbed Product Pro plugin. Go above and download the add-on and install. If you never installed plugins before make sure to READ all instructions and download the one for your ZC version.
