In answer to your first question:

I do not have a tablet, but I have a ASUS laptop with a touchscreen. The touchscreen turned out to be a novelty only. It is workable but a bit more cumbersome using sliders.

I have two problems with using a tablet that have kept me from buying one, the touchscreen just isn't as precise as using the mouse. So for me it gets annoying.
Second the screens are just to small. You working on a much smaller view so the chance you overlook a flaw is greater. If you are only displaying small photos like we post here it might be ok.

Yesterday I bought a new top end 13" macbook pro to take with me on vacation, this will meet my need for something small to travel with. The ASUS is huge compared to it, but I would much prefer the larger screen over the small.

So in answer to your second question, I have no recommendation for a tablet. The option I went with was a smaller computer.

I will throw one other thing that always pops in my head when thinking about a tablet, how am I going to move all those huge RAW files on and off of the tablet.