It is possible to open Ascendant Chest without drinking from bottle. This chest was in Aphelion's Rest. Screeshots. https://cdn.discordapp.com/attachments/536735242581704704/597227511126032424/unknown.png https://cdn.discordapp.com/attachments/536735242581704704/597227622619021317/unknown.png
You can open any of them if you manage to stand/hover next to them. You don't need to be Ascendant to open them, just to see the chests and the platforms.
Yes. I believe there are a couple that can be opened w/o being ascended.