Re: RF Limmiter
The short answer is, you can not know. You can buy a reel of these diodes (manufactured at the same time), and do a test on what limiting power they turn on at. The limiting power is a function of the PIN diodes intrinsic layer thickness, which is not something they are going to control for limiting applications in a diode designed for attenuators.
You might want to choose a different diode, as the thermal resistance of these puppies is 500 degC per watt in the SOT23 package--not a good choice for a 1 watt limiter application!
You might want to experiment around with different topologies. Kspalla points out that you can use a schottky diode to help to turn on the limiter diode at a more predictable power level. You can also use two limiter diodes spaced quarterwave apart to do the same thing.
Rich