I can't test it myself.
If I log in without a username, the list of players only shows the nickname and the application date.
Do tournament participants see each other's ICQ and Skype numbers if they log in with their nicknames? This information is needed for players to communicate.
And do they see the list of applications and comments from the organizer?
Yes, that's correct, ICQ and Skype are only displayed when logging in with a username.
The list of applications is only for the organizer, and the comment on their application is displayed to the target user in the "Tournament Participation" panel.