not sure is this the right place to post: i think the 4 twists are:
1) 20 houseguests, several double evictions, the first one will send 3 people home, followed by 2 until Final 11/12 is set
2) Diamond HoH: Enables to veto the first 2/3/4 houseguests nominated for eviction
3) If this Hoh wins this week's HoH, he/she must win the next one, else he/she will be nominated for eviction
4) Old vs New (Returning houseguests vs New Houseguests (10 on 10)