I'll have a patch out soon for the Secure Ring and passability issues.
The Fishman General Garb is in the Palace of Water, and the Timer Ring is in the Gemstone Cavern.
There's a dialogue option that lets you go quickly between the new land and the Overworld in the Alchemist's Cave. Once you've cleared out the encounter in that screenshot, you'll get another shortcut through a dialogue option.
As for the pillar, I probably forgot a doodad. I'll correct this as well.