1) how does tails spoof your device identification Id's/fingerprints ?
The only spoofing of device identifiers performed by Tails is the spoofing of the network interfaces MAC address.
2) is spoofing done by tails or tor ?
It's done by Tails.
3) how do I confirm that the data websites have access to, is spoofed?
The websites don't have direct access to hardware identifiers. Fingerprints can be confirmed by trying to perform known fingerprinting techniques and ensuring that the response doesn't match the expected response and isn't meaningfully distinguishable from other users. It's possible that unknown fingerprinting techniques exist. Due to the method of fingerprinting being unknown, you obviously cannot check to see that such information is spoofed.
4) when does tails spoof my data ? When booting from USB in live mode? Or when installed on a USB? Or both ? Also does persistent storage have anything to do with storing device ids ?
The MAC is set to a spoofed value during the operating system boot, before any network connection is made.