Vortex Sound Research

Considering buying one of these but I am still a little confused even after reading the manual. How many layers of recordings can playback at once? Let's use the first 2.5 second setting as an example. If I record 5 seconds does it create two 2.5 second "clips"? What if I record silence for 5 seconds.. does it erase and go to playback silence? I am not sure if the delay lines are specific to each recording or define the maximum recording lanes available. Does it always phase out the oldest recorded material first as you add more? Trying to get an idea of how much you can build before it starts to remove things and how it decides that. Any help is appreciated!