1) There was a <div> tag above the <html> tag. There should never be any html above the <html> tag. That is the code I moved lower.
2) I'm not sure. I hadn't seen this before and it wasn't on your pp_confirm page. I really can't explain how it got there. I thought maybe you had edited the code and were trying to add your shipping base charge as a tax and it got added then? Really I can't explain how it got there I can only observe that it was there.
3) I changed the way it was passed to paypal. So when passing the paypal instead of using the price as the price and the quantity as the quantity, which when multiplied wouldn't add up to the correct row price since you have a base charge... I changed it to use the total price (price*quanity + base charge) and set the quantity to 1. That way the math will add up and paypal won't complain. I did that on both the confirm and pp_coinfirm pages where the data is sent to paypal for processing.