Is it possible to add text und checkout in product display?
 

I would like to add text under the checkout button on the product display page. I am almost sure it would be added to product.tpl but not sure of exact coding.

For this and any changes you want to make, start with Webmaster mode. That will show you the template you need to edit.

For this though, yes, it is product.tpl to start with if you want the product display page, although this by default has an Add to Cart button which I presume you meant, as the Checkout button appears in the checkout process.

If you were to follow the x-cart format, you would put the text in a language variable which you would have to create. But there are no rules, you can just add text straight into the template. Edit the page in a decent ftp program where you can put the page in layout mode and you will see that most of the page is just simple html tables. If you know html coding then just go for adding the text where you need it, probably under the code for:
{include file="buttons/add_to_cart.tpl" style="button" href="javascript: if(FormValidation()) document.orderform.submit();"}

Moving to Template Editing

Add text to products!
 

Can this be specific to each product or will it need to appear on all products?

If you put something within the loop for each product on the products page, it is going to loop and repeat each time.

If you want something product specific, perhaps put it within the product description itself.

ok, that is what I decided to do was put in product desscription itself. Thanks for your help!