If you do not unlock everything in the season one pass in the 35 days or whatever are those rewards gone from you forever? Like you can't have access to them, like if you don't get to the tower skin you will never get that tower skin? Or does it stack into next season?
I let my chest cycle and crown chests lapse a lot as it is stressful to keep up with it.
yes you have to unlock everything within the 35 days to get it.
the new crown chests change means that you are never left with 'wasted' crowns (e.g playing when your crown chest is not there to fill) - if you have pass royale and earn crowns they are added to your total throughout the season! this should make it a lot easier to collect crowns and earn those pass royale rewards.
once they have been unlocked and claimed the season 1 rewards are yours to keep!