No.
Sure. If you have ETH in a Metamask account you can move it to your Trezor. Note that there are two types of Metamask accounts in your case – native Metamask accounts and Trezor connected Metamask accounts. If your ETH is in a Metamask account connected/linked to Trezor, then the ETH are already in your Trezor. Please check the Receive Address again and if it’s in a Hidden wallet in your Trezor.
My guess is that you transferred your ETH from Coinbase to a native Metamask account, not connected to Trezor. So you can simply make a Receive Address in your ETH account in Trezor and then transfer the ETH from Metamask to it. Please check and double check that the Receive Address is correct before you do the transfer.
Note that it’s not necessary to go through Metamask at all when you transfer ETH to your Trezor. You can do it directly, since ETH is supported in Trezor suite. Only coins that are supported by Trezor, but not Trezor suite, may be necessary to see/handle through a 3rd party site like Metamask.
No.
Nothing. You shouldn’t worry about them.