My tablet is a 10" Android (Acer Iconia A200). There seems to be a fair amount of debate over 7" vs 10" but I feel I would find a 7" to small for browsing websites comfortably and am not worried about the extra bulk.

The only web site with a crossword I visit is the Guardian. Their crosswords can be completed on line but I do the crossword in the pare and only go there to cheat.

(And I usually only attempt Rufus in the Guardian - mostly I just do the ones in the Eastern Daily Press. I have completed an Aurcaria without cheating but it took me a couple of days and I found it a real struggle)

A couple of resources I sometime use when I'm stuck:

The Crossword Solver
Andy's Anagram Solver