For transaction signing, QR codes would probably be the safest way possible. Not sure exactly how to get it all set up myself, but I know there are some users out there who do this.
I agree. You would have very few to no potential attack vectors if you never have any hardware touch both your offline computer and your online computer.
I'm not storing on the floppy, I'm talking about using the floppy to store the signed message that I generate on my offline computer and transfer to my online computer.
I think you would need to have a pretty high level of paranoia to not trust a USB drive, especially considering the fact that you can easily purchase one without a potential attacker knowing ahead of time that you will be buying one nor where you plan on purchasing it from. This would still leave the possibility that someone with physical access to your USB drive could infect it with some kind of malware however you could prevent this by keeping it in some kind of safe or other location where an attacker cannot access it.
To answer your question, yes a "floppy disk" would be a safer medium to use to sign a TX when defending yourself from an attacker, however you would open yourself up to additional mishaps (for example the TX that you are signing gets corrupted on it's way to your offline computer and you end up signing a TX that you did not intend to sign)