Hi,
You design a LNA ckt for a NF and gain. So you use the equations back and derive the noise which is pretty tedious. The other approach is you can use ADS and measure (simulate) the gain and NF.
If you're using SpectreRF, the answer can be found easy. You can check NF from "noise" or "pnoise". For linearity, you can perform "pss" simulation and see CP1, IP2 and IP3. Read SpectreRF manual for more details.