Do we "lose out" on content and rewards that are unlocked in week 1-3, for example, if we only reach level 40 and start the season in week 4?
I want to know too.
I think you can get all 4 Agent Abilities throughout the season after they launch ( Within the season ) . But i do think there are some events exclusive to the week.
The manhunt is available for the whole season; so you can do all 5 hunts on the last day if you a crazed man/woman! However I believe the events like the polarity event are timed and you would miss out on them if you are not 40.