We are working off of past history here, as production has not 'officially' announced that it was going to be 2 episodes back-to-back but... as was the case with Gabon, it is shaping up to be 2 episodes back-to-back.
With the visible knowledge that the "1st IC" includes a reward and then the confirmation of a "1st Reward Challenge", it can be assumed that we will have a 2nd IC to contend with as well as 2 separate Tribal Councils. The best/only way to do this in 2 hours is, simply, 2 episodes.

It makes sense that we aren't seeing anything regarding the castaways performing in a challenge beyond the first RC/IC. (Outside of a few 'future challenge' vidcaps.) But I am keeping my eyes open for any hints as to sit-outs or confirmation of challenge specifics.

If I'm thinking correctly, on the horizon we have; a muddy-sumo challenge, a tossing buckets of water challenge, a swimming challenge, a koi puzzle challenge and a puzzle wheel challenge that have been sneaked but haven't found a placement. Any of them could be the 2nd IC. OR the 2nd IC could be something completely different.

Suffice it to say, the premiere will contain the intro, the leader/weakling twist, the 1st combined challenge, a tribal council, a reward challenge, an immunity challenge and a second tribal council.