First of all thank you for reading my guide! @alwayssaturday
A "hot" wallet means when you keep it connected to the internet. When you download a wallet, you are basically downloading a key generation software. When you disconnect from the internet and then generate your keys, but later on you go online again, it defeats the purpose of generating your keys offline.
How the blockchain works is: you don't need to register your adress online, but you will the right key generation software (wallet). The beauty of how the blockchain works is that it will recognize any address created by the software. You *dont need to connect to the internet first to "register" your addresss.
The safest way to protect your keys, is to generate them on a device that will never be connected to the internet again. Even if the device were infected the keys could never be stolen through the internet (there are other methods but it would require the hacker to be near your device).
If you make an air gapped computer it means never connecting it to the internet again. I would recommand using an old computer for it.