If I have a traccar server instance, and a device with ip set to that instance but not yet added via web interface:
1.) Will traccar save those data sent by the device?2.) If I add the device after it has sent data, will traccar report it as online?
No.
Depends on the device. For some devices you would have to wait till it re-connects because it sends identification only one per connection.
If I have a traccar server instance, and a device with ip set to that instance but not yet added via web interface:
1.) Will traccar save those data sent by the device?
2.) If I add the device after it has sent data, will traccar report it as online?