The question's pretty obvious. I'm following Ascension's tutorial on antique maps but I have trouble finding some of the tools he describes (for instance, the airbrush is now a toggle option for the brush tool). I can't find any square markers either. Does anyone know where to find those? Also, I'd be really stoked if someone could find a site given a short summary between the differences of photoshop versions (kudos if you can give me the exact version Ascension used!).

Thanks in advance.