[zuluclayman]

This was to be my addition to this discussion - academic versions are available - you need to be able to provide items of proof of your eligibility.
Some vendors aren't as strict as perhaps they should be about this requirement.
As far as I am aware (having had various academic editions of different software as a teacher and university lecturer) there is no difference in capabilities in from the commercially licenced versions.
Another option is Photoshop Elements - has lots of the functionality of the full version without some of the more design/photographer professional-oriented features.
GIMP is an excellent freeware package with many of the features of Photoshop.

 

[zuluclayman]

The alpha channel stores the image's info, particularly used in image editors for transparency and masking.
There are numerous tutorials out there for using the alpha channel for various functions.