Werden Ihnen Gebühren für die Übertragung Ihres Guthabens vom Hauptseed zur Passphrase berechnet?

1. I prefer the T for this very reason, everything can be done from the device. It helps to mitigate attacks from key loggers, etc.
2. There is no „they“ charging fees (unless you mean everyone using/hosting the network). When you use a passphrase, it creates completely new keys. As such, you will encounter the same fees as making a transfer between any addresses, passphrase protected or not.

Who is „they“? Trezor doesn’t charge anything, but of course you pay fees when moving funds on chain…

“ I would like to add a passphrase and the T can be done from the device, instead the one needs the keyboard. Does that make a lot of difference to all of you?“

Both support passphrase, yes you can input passphrase on the T device itself. not much of a difference.

„Do they charge you fees for moving your funds from main seed to passphrase

I’m guessing you mean transfer to another wallet, in this case, yes there is a transfer fee, depending on the network used.

I highly recommend the model T over the model one.

Moving coins from a 12-word seed to a 13-word seed (using a passphrase) is the same as any other transaction (2 different wallets), so network fees would apply.