I am past the Battle Tower part of the game(doing side quests for it actually) and just remembered two things I wanted to do in Broken Valley but assume I cannot anymore.

The first was the Hellgate. I beat it but reloaded to save the last monster just in case a quest required it...then forgot about it. Was that my only chance?

Second. The big fortress near the Hellgate that has a cutscene showing the doors being blown off...when I entered the complex, the voice in my head told me to leave or surely die. I explored anyway with the intention of reloading an older save and skipping it until a quest sent me there. Again, I forgot and also found no quest for it.

What was the purpose of these two small areas? You can go ahead and spoil it for me and say I can go back later when the "fog has cleared" so to speak.