Can you please tell me how to get to these questions? (The Witcher 3: Wild Hunt)

You'll get to the main story. At the end. Kill it and move on.

Maxonior
Wise words!

where the ship is in the north, but the door is only according to the plot, so it's right to forget it and move on.

simple - play

I will reveal the veil of secrecy) this is a place of power and a chest.
You will gain access when you go to look for the Sun Stone. And do not try to get through the back entrance (exit by square) - there is a door that can only be opened by square.