Rock is not a good choice for a couple of reasons.
1 - It creates a porous surface that water is going to penetrate anyway, rather than a barrier.
2 - If you ever have to get under the deck, you've now got rocks to crawl on - NOT FUN!
Regrading the soil shouldn't be too difficult with regular digging implements. If you're working in tight quarters, get yourself a camping shovel, which is about two feet in length and easier to work in a confined space. If you've got hardpan soil, this is good for getting the water to drain away from the house, but bad to have to dig in. Rent yourself a rotohammer with a spade and chisel tip. This will make digging a breeze.
If the space under the deck is particularly tight, you can remove sections of the deck boards to gain access more easily.
You only need about a 1/4" per foot of slope to get good drainage away from the house.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!