1- If you player's training workload is set as "light" or "normal" your player's condition increases 3% everyday. If you want to increase it a 2% you need to go to the "activity" tab in your player's profile.
2- World Cup are played every 2 seasons.
3- Sunday is a day set as free, however there are competitions other days: Custom Cup on tuesday (premium users only), World Club Champions Cup on thursday and NT matches on fridays.