Hi Yves,
For printing forms, we use the Printable View link which is usually at the bottom of the page. This link is really just using the printerfriendly skin in the site skins directory so if you need to modify something, it's rather easy.
For the PDF, creating a pdf of the form submission is something I can do for you as a Form Submission handler. Submit a quote request on my website so I can get your email address and we can see how much this would run cost wise.
Joe, the only drawback to the Printable View option for printing the form is when using multiple pages on the form one has to enable the "flatten pages as groups" option in the module settings, view the form in Printable View and the go back and disable the flatten pages option. If we had a way to show the form as a single page, for printing purposes, that would help but it's not really a high priority.
HTH,
Joe D.