Is this a generic bootable device or are the files specific to the PC it was created on?
It keeps the current PC drivers, thats all.
If it is generic and it will get you to the recovery screen on any machine how do I select which backup to use, do I have to copy it onto the same USB device or a different one?
Yes, you can if you have similar hardware and operating systems on all your machines (or you can include additional drivers while creating the recovery media). The recovery media relies on the windows recovery environment components, which are almost identical in all OSs, driver versions can be different – so it’s recommended to have a recovery media per operating system in your environment.
Wanted to clarify, you used 1GB USB stick for recreating recovery media, right? Could you, please, format it and check again without including additional drivers and let me know the result. Thank you.