I highly doubt there are going to be any Primes or Legends in this set. This set is technically not part of the HS Series; Pokemon.com lists Call of Legends as being outside of HS (under Trading Cards Expansions, Call of Legends is placed in its own category).
Also, the official press release mentions nothing about Primes or Legends, and, considering this is a set that promotes Legendary Pokemon, wouldn't it have made sense for TPCi to not have included Mew and Celebi Prime in Triumphant and place them here (thereby also keeping the 6 prime per set rule that the other HS expansions had)?
In terms of what cards will be in this set, we know there are 14 cards we didn't get from Lost Link (11 Pokemon and 3 T/S/S) that will most likely all be there. There are also 5 other T/S/S cards from the HS series we didn't get (PlusPower and Rare Candy from Reviving Legends, for example). We also know that Hitmonlee and Houndoom are being reprinted (plus, most likely, their evolutionary families as well, which means another 6 cards right there). If we include the promos that were given away in Japan with the first HS expansion and their evolutionary families (the promos with the Sugimori artwork, like Totodile, Mareep, etc.), that would give us another 16 cards.
So, that's a possible 41 cards out of 95. This leaves 54 cards not accounted for (possibly 46 cards if they include Energy cards in this set)