1) So are you saying that there is no way to do an offline paper wallet like Coinbase offers?
I didn't know that coinbase offer an offline wallet, but even if they did I will not recommend using it the same as their exchange site.
2) If I buy a desktop wallet for my PC, can I put it on a flash drive and erase from my desktop so that even if my desktop is hacked I am safe?
You can't buy a desktop wallet, it's just a secured wallet(software) installed on your PC.
Considering you're talking about buying hardware wallet. Even if you have an infected PC you can use this HW safely coz HW can't be infected with malware. Just make sure that you will never share the 24-word recovery phrase which will be your backup, save it on a safe place offline for your own good else your funds on your HW can be compromised.