icon system / retro kits / full intro player career mode

anyone knows how the icon system in career mode will work? I have idea there is only a limited amount to be used?

and how does the retro kit system work? You get them though challeges? Is it seasonal only? and can they be used for career mode? I always buy the game on sale so I hope I dont miss out

and lastly is full intros back for player career mode?