I went into paypal, express checkout was enabled so I requested API credentials which gave me a different username, password and API signature. I then went into my checkout page and clicked on the Server behavours tab and went into the authentication by paypal express and entered this new info here. I tested this, it when I clicked on the Paypal button at the top of the checkout page it took me through to the paypal login/ pay without an account page successfully which it didn't do before however no value or order information is transferred over from the checkout page so there is nothing to say how much the user is paying? If i tried filling in the form on the checkout page it transferred to paypal but said the cart was empty.
I then looked at the source on the confirm page and compared to the one i had previously working as I changed some of the calculations columns, I changed the new confirm page to the same, ie adding RealPrice:
<input type="hidden" name="amount_<?php echo $eCart1_Index+1; ?>" id="amount_<?php echo $eCart1_Index+1; ?>" value="<?php echo WA_eCart_FormatNumber($eCart1->DisplayInfo("RealPrice") - (($eCart1->DisplayInfo("RealPrice")/$eCart1->TotalColumn("TotalPrice")) * $eCart1->GetDiscounts()), false, 2) ?>" />
Success this worked! I did a test transaction and it returned me to the success page, however thats about where I had got to last time, it doesn't return the Paypal transaction number which I understand is what you mean by this method is not so good. so now I need to figure out how to get the express bit to work if you say that this will return a transaction id? I have looked at the code on the checkout.php page but I can't see where it gets its info from to transfer the values to paypal?