Ensuring a Secure Future for My Children with Bitcoin

• I have two children and have created Bitcoin wallets for both via bitaddress.org. Are the generated wallets "secure," and can Bitcoins only be withdrawn using the private keys that I printed? I have deposited 0.00025 Bitcoin into both wallets as a test via Phantom Wallet. Will the wallets expire at some point, or does the money stay there indefinitely? Can you check these wallets?
• https://www.blockchain.com/de/explorer/addresses/btc/12TD1Et54xgHqHq9giVfJuzRMYhAUAJ4Jw
• https://www.blockchain.com/de/explorer/addresses/btc/1Pxpd3YCBHfTKfXyQNaucNcfcHFhYwFfPe
• Is it secure to store the private keys in paper form in a bank safe? I want the Bitcoins to be safely stored for the next 10 years.
• How can my children withdraw the money from the wallets in the future? I can only find providers that require their own wallets. I couldn’t figure it out myself. What if no provider exists in 10 years to withdraw from these wallets? Where can the wallets be imported?
• Over a 10-year period, does investing in Bitcoin provide a better return than keeping money in a bank account?
• I have terminal pancreatic cancer and want to leave my children $1,000 each. How can I ensure that my children will have access to these wallets later? I want to make sure that my remaining savings safely reach my children.

My goal is to leave my children more than I can currently provide.