Question about Garmin Zūmo XT

Does not fit

I can't answer the question about the holder. It's my first navigation device. I've got on quite well with it in the meantime, but I'm certainly not very "gifted" with electronics. What certainly doesn't work well or at all is planning trips on a Mac and transferring them to the sat nav. . . but that seems to have been a difficulty (still not solved) for Garmin since the beginning.

Not to my knowledge, as Garmin also has different recordings depending on the device.