Akasha or "the Root" is not an entity though, its more like a place or phenomenon. It does not have any will to exert anything on anyone, it simply just exist. It is the embodiment of all of existence, everything that ever was or ever will be. Some argue that there is only one Root and it encompasses all universes, timelines, and even higher dimensions but I have not seen any official confirmations of that.
The only official power level rating we have lists Type-Mercury on top, I believe, and a full powered Arcueid as 2nd, and Void Shiki as 3rd. Void Shiki is connected to the Root but we can assume that her ability to manipulate it is limited; since Arcueid only has the power of the Planet Earth, sufficient manipulation of the Root should be able to erase the Earth's existence.
It is possible to kill anything with sufficient manipulation of the Root, the unabiltiy of the MEoDP to kill some things is a limit of the person and not the Root itself. The nature of Balor's eyes are unclear, we do not know if it manipulates the Root like the MEoDP does.
No, Bodhisattva and Earth Goddesses are not above Akasha, they are only entities of the Earth and the Root goes far beyond the Earth. I played Extra and I do not recall any such claims but even if it was there, it is unclear how reliable such claims are, as it could just be one man's myth and legend, unlike the Root whose nature and existence is recognized by all mages or the Ultimate Ones whose existence and powers are absolutely shown to exist.
The Extra universe itself is highly iffy, honestly, and it is unknown how much of it even applies to the rest of the Nasuverse.