well, to be honest i wouldnt mix SO many crabs together. Personally i would pick 2 out of the three species of crab you mentioned (excluding the arrow crab, as they usually like to stay in the water column and not on the rocks). I'd probably go with another sally light foot and the 3 emeralds and forget the porcelain, just to avoid possible war between them, although you may get lucky and never see them fight too... who knows, but thats what i would do.
As for the hermits, i tend to like the dwarf blue legs the most for sand cleaning, which is IMO pretty much what the nassarius do too. If it were me, i would probably get 15-20 dwarf blue leg hermits, but my opinion is biased as well. I'd probably get 10-15 astreas, maybe a couple of Mexicans, although not many as they tend to be more expensive and do less work load. And maybe 10 or so nassarius.
That would put you at:
20 dwarf blue legs
10 astreas
10 nassarius
3 emerald
1 sally light foot
1 arrow.
With all of the other stuff you already have, this would be MORE than a sufficent cleanup crew, in fact if you wanted too, you could even cut down a bit and not get as many hermits.
I'd probably shoot for end result
20-40 hermits (however many you feel necessary to keep your sand white)
10-20 astreas (my personal favorite snail)
5-10 turbos (which it sounds like you have)
5-15 nassarius(just to help stir up the sand some)
and whatever other crabs you like, such as the arrow sally light foot, and the emerald.
This is of course just my opinion. =).