So as I understand it, my seed is my extreme backup if all else fails i can access my btc again anywhere anytime with my seed words. Then my hardware usb device is a functioning device for signing transactions, i can use it to send money from my encrypted wallet that has my seed stored in it
A hardware wallet is useful for signing your transactions safely, decreasing significantly the chances some hacker steals your coins. Internally your hardware wallet works based on your "wallet seed" (to say so and to keep it simple) which it will usually show you only once, when you create a new wallet (like a reset to factory, but which creates a completely new seed).
A hardware wallet is an electric device that has a limited life span (some days will stop working), so for your coins' safety you need to keep the wallet seed safe and offline/physical. Depending on people's preferences some save it on steel plate. Yes, it's fire proof, but if you need somebody else to engrave it you have already a problem (you should not give the seed to anyone, you know that, right?) and a seed plate stands out more than a piece of paper. On the other hand, many just cannot be careful enough with just a piece of paper.