Is there any freeware I can use to create interactive PDF documents like the one linked to below, or can it only be done using Adobe Acrobat, the full edition?
The effects I need are the translucent hint box in the upper left hand corner, clicking a number to set a checkmark on top of it, and the reset button at the end of the first page.

http://forms.cgaux.org/archive/a7060f.pdf

I found the answer nicely explained here :
http://www.coedu.usf.edu/IT/viewlets/acrob...iewlet_swf.html
The coedu tutorial is based on Acrobat Distiller. Unfortunately, when you want to download distiller, you need to pay for it.
Maybe there is another way of thinking.
In the example you show, this pdf form cannot be saved on my PC. I can only fill it online and print it.
So, no need for this form to be a pdf one, it can be any kind of form.
Then, you could consider using any kind of forms, for instance have a look here
http://www.google.fr/search?hl=fr&q=html+forms&meta=
and mainly here http://www.cs.tut.fi/~jkorpela/forms/
I love html forms because you master them, they are on your site, you maintain them using your usual backup/restore tools.
If you don't like html and want to use ready-made forms, you can simply keep goggling on "interactive forms" and simply skip the commercial tools when they don't have free testing downloads.

I don't really do a lot with PDF, by creating them, usually I just export a document file, but I tried and made quite good PDF files using PHP and TCPDF class for PHP, it's very easy to use and you can really make a lot with, but it requires some time, even though I liked it, when I learned how to use it, in their site there are examples of what can be made or those examples were in the archive with the tcpdf class, can't really remember, but it's really great.

http://tcpdf.sf.net/