Thanks for your reply.
So I should wait for Joomla 3.5, my site is made with Joomla 3.0...
In question 2, I mean that in your demo for example, you can't order a Gift Certificate for an arm massage and a finger massage. You have to order 2 Gift Certificates.
Ok for the expiration date in the admin, but it should be printed on the Gift Certificate too.
For the pdf feature, don't hurry for me. I need to build my site and wait for Joomla 3.5.