probability of psychical collisions and RX timing

Hello,

  1. Are there any data on how long it takes to turn on RX or to change channel? Or is it so fast that it’s insignificant?
  2. Are there any data on actual probability of psychical collisions? Specifically If I’m using different pre-amble codes on one channel? (I can trasmit two packets in one moment over each other without problem… but it would be nice to have some “official” data on it)

Thanks for reply!