Obviously you can create multiple wallet addresses with one Trezor hardware wallet and just one seed phrase. However, I don't know if one seed phrase has more than one BTC address, if our Trezor hardware wallet has problems such as a dead screen or other problems, other BTC wallet addresses (not the main wallet in Trezor) can be accessed in other BIP39 wallets or not.
Below are some references that might be able to answer some of the points you mentioned above.
-snip- the BIP44 standard for Bitcoin hierarchical deterministic wallets proposed to respect the address gap limit, which is also used in Trezor Suite, limits the number of fresh addresses created under one account to 20 until you have used at least one of them therefore, after using at least one address you can create more than the inital 20 limit.
The recovery seed is a crucial element for the security of your Trezor hardware wallet. If your device is lost, damaged or stolen, you can use your recovery seed to restore access to your entire wallet, passwords and other data associated with it. The process is simple; you only have to enter the words of your seed into your new Trezor device. (You may also use any other wallets or applications that use the same standard as the Trezor.)
In my experience
https://bitcointalk.org/index.php?topic=5467802.0, I have 4 BTC wallet addresses in one trezzor with one seed phrase, because there was a problem with my trezor, I was forced to access it in the BIP39 wallet (I use a trust wallet here) where only my main BTC address appeared.
Instead of using a Trust wallet to transfer the seed phrase from your damaged Trezor, another alternative that I think is safer, even if you don't move it to a hardware wallet again, is to use Electrum, which is installed manually on Tail OS which is stored on a USB flash disk. DWYOR.
My advice is that if you want to create other addresses on a single hardware wallet, make sure to also create a phrase for each wallet address. This is done in anticipation as a backup so that the funds we store there can be accessed safely and well in all conditions.
In my opinion, the suggestion of creating a new seed phrase for each wallet address is too much. It's the same as having to reset the hardware wallet for that.
A fresh address is a newly generated address that has not received any previous transactions. It is recommended to use a fresh address for every transaction, as this benefits user privacy.