Where to paste HTML to add Paypal buttons & Can I change the word "Products" in Drop d

1. I've created "Add to Cart" Paypal buttons but don't know where to paste the html in my MarketPress lite plug in to make them appear.

2. I'm selling Tshirts and bumper stickers. I'd like to change the word "Products" in the drop downs to something a bit more pithy. How?

3. I'd like to use the Product Category widget in my TwentyEleven theme. On my "products" screen I see they are all assigned in their proper categories. When I added the widget, the drop down is there with the two categories, but when I click on either one it says "no products" ...What am I missing?