Diameter can be reduced but not increased.  Theoretically you can cut diameter all the way down to the hub.  Realistically however, a couple of inches would be the maximum reduction you'd want to make in diameter.  The problem is that the blade edges get extremely thick even when reducing diameter as little as an inch.  While this may provide a very tough blade edge; thick, blunt blade edges are tough on performance.

Pitch:

The rule of thumb is that you can increase or decrease pitch by 2 inches.  Bear in mind however that large propellers, and NiBrAl propellers especially, are very tough and resilient.  Reducing pitch 2" is no problem, but while it may be possible to achieve an even and well distributed 2 inch pitch increase on the table in the shop, this may not be maintained when your props are put under pressure.  Better to stick with no more than 1 inch when talking pitch increase.

Cup: 

Cup can be added or removed from a propeller in 12 steps ranging from .000" to .182". (Applicable to some, but not all, I/O and outboard props)

Bore:

Bore can be increased up to the maximum allowable dependent on the hub size of the propeller, and decreased through the use of bushings.  Cannot be changed on I/O and outboard propellers.

Rotation:

The rotation of a propeller cannot be changed.

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