The 2nd season is definitely darker then the first, with some great (and sad) things revealed about some of the characters.
As for plot points getting revealed and such, it's very clear that Alex Hirsch has everything planned out from the very beginning. (Something which shows like Lost could've benefitted from.) Also, A.H. knew there was going to be a lengthy mid-season break, so he's treating season 2 kinda' like two seasons with their own premiers and finales so the pacing is better and it would be broken up into satisfying chapters.
Yes, plot points are getting revealed, but they definitely needed to get brought up in order for the mid-season finale to happen as well as tease mysteries and events that'll probably happen in the second half of the season.