Capacity of LoRaWan gateway (iC880A)

I want to connect roughly 50 nodes which sent a payload every 10-15seconds. I’m deploying a private gateway in the center of my coverage area.

So I was wondering what the (theoretical & practical) limitations are of the number of connected nodes for a self-build gateway based on a Raspberry Pi w/ iC880A is.

To my knowledge the gateway has 8 channels; so there could be 8 nodes simultanously sending packages at a given moment. But what happens if you exceed this number?
Will the transmission just be discarded? Or is the node (LoRaBee) smart and sends a request first to the gateway and if available it sends? Or does the node just transmit regardless who or what is listening?

But off course not every node is connected the whole time. How long does a transmission of a payload take?

You better ask this here

Afaik- Lora is the wrang technology for what you are trying to do

The way the band is regulated prevents this. You are only permitted to transmit 1% of the airtime (duty cycle).

By default, each channel on the iC880A is setup with a different spread factor (speed/range).