I don't think the OP is inquiring about the 13 inch model or a cinema display. He is simply asking if a tablet and CS5 would work well on the 11 inch MBA.
How will performance be? Well that's the question most people are wondering. Myself included. Ideally, I'd like the MBA to handle light photoshop edits on raw files. No intensive actions or filters. Just enough post processing for blog worthy material.
Also, at times, clients need small text edits, and layout/design edits when I'm not at work. Ideally, the MBA should be able to handle this. I also use a wacom tablet.
To the OP, not much has been answered regarding photoshop and the 11 inch MBA, but most people come to the conclusion that if you're looking at this as your sole workhorse computer, it might be better to consider another option as the 11in seems to be the perfect "companion" computer.