Paypal pay,emts pro offers both, you can remove the checkout form from the checkout page is you like and only have the option to use express checkout.
Some people prefer to enter the CC Info on your site, some people prefer to use paypal, it just gives the buyer more options.
Since there are 2 payment options, you need to add the instructions fields to both payment workflows.
for the Direct payments workflow, the instructions field goes on the checkout page, you add the set session variable to the confirm page and add the hidden form element to the confirm page.
for the Express Checkout workflow, add the instructions field to the pp_confirm page and add the set session value behavior to the pp_confirm page.