Is there a PADS version for students
It seems that ECAD (as opposed to MCAD) vendors are not very interested in getting students to learn their tools. As an example, Altium charge £100 a year for a student version while Mentor don't even offer one.

In these cases, I often advise just getting a "free unlimited trial" version from the internet. There is nothing wrong with this, as long as you use the software for educational purposes only.

As for which package to get, you can learn with pretty much any package - KiCad, gEDA, even EAGLE (*shrug*). However, if you choose a package that is commonly used in the industry, such as Altium Designer, PADS, OrCad etc., you get the benefit of being able to add additional line to your CV.