I think around 1 year before we done with season 1. and season 2 will take a couple of years to finish.
we are fixing and adjusting the game all the time, but we are trying to always keep your save as best possible.
if bugs/errors Haseo can fix most issues, so u dont need to worry about that.
so yes, u can carry your save. the game is "linear" for season 1, but sometimes we are content in early stages, this to make it more fun to play in early stages. but most of the time u can go back and do those side-content.