Good afternoon,
Once a paper wallet private key has been sweeped, can Bitcoin still be safely sent and stored to the address of the sweeped private key? And therefore can that priavte key be sweeped again in future? Or after a private key has been sweeped does the address become invalid?
Thank you.
Keep your private keys in different backup, and I don't see any threat of security there as long as you don't exposed your keys towards untrusted sites.
Avoid using your emails for shady transactions like kyc registrations and other potential risk that may breach your security. Having printed paper wallet, should be done together with it's QR code and that's reliable and safe. But, I don't try to generate btc private keys yet, only for erc20 tokens.