Yeah, I get that a lot - trouble is on the forum you can’t stand next to them although, UK travel restrictions be damned, I’m tempted for some cases to go and fix it that way!
For Joins, Rx1 is 5 seconds - so you only need to wait 6.5 seconds to know. Don’t confuse this 5 seconds with the other 5 seconds I’ll mention in a second.
Rather like in your gateway console where you clicked on the line and got the event details, you will get the same for the device log - scroll down in that box and it will show you the gateway info.
You don’t, it’s meant to be baked in to the code - if nothing arrives after 5 seconds, wait 1 second and listen again.
Depends on the context of what was being written - I could just as easily say it takes 10 minutes if the device has to try a few times.
Ideally you need to get to a point where your gateway is showing it is transmitting the Join Accept before moving on to the Pi problem.
Can you look at the device log and see which gateways it is being heard by.
Do you have another device you can put on to v3?
v3 is far more compliant so more relaxed implementations of a LoRaWAN MAC are going to struggle to talk to the NS.
And then there is the info Jac has mentioned regarding timings.