Over-the-air-activation OTAA with LMIC

This refers to "activate" a NODE based on ATMEGA and RFM95W with LMIC1.5x
I'm a little lost in TTN:
ok, I could follow the procedure with ttnctl-windows-amd64 up to step 8. Get info about a specific device
There I get
AppEUI: which I already know from step 3./4.
DevEUI: created 8 bytes of true random (RFM95W does in contrast to RN2483 not give a unique hardware-ID)
AppKey: also known from step 6.

my confusion is: LMIC needs also the following (also confused about "session")
- LoRaWAN NwkSKey, network session key DEVKEY[16]
- LoRaWAN AppSKey, application session key ARTKEY[16]
- DEVADDR which I've choosen out of "tth-zh address space"

1. is AppKey one of DEVKEY or ARTKEY. how to find the other?
2. could I use them as given from ttnctl or do I need to shuffle the bytes around as mentioned above LSBF/MSBF
   please give me dummy a clear example for DF FD 57 53 B0 57 3D CA F1 6A CE CD D1 BD A2 8A
3. how do I register DEVADDR or will it registered at first usage?

thanks for your kind help, urs