Do any the other Daedric Prince's realms have earthbones to anchor them (e.g. Haskill)?

No.

Earthbones are (parts of) et'Ada that took part in the creation of Mundus, and enforce most of the physical and metaphysical laws. These are applied in addition to the already existing rules of the Aurbis, though they may at times counter act them.

The Daedra made their realms out of themselves, so they enforce all those rules themselves.

Haskill (and by extension, Dyuus, for while they aren't the same people, they occupy the same role) is... strange. I have a few theories on Haskill that I unfortunately have yet to fill in the missing pieces of information to really push forward an idea on him. My best working model is that Haskill is the Anuic sustainer of the realm that keeps the power of Sheogorath from making it change radically and (dangerously) drastically at the drop of a hat. Of course, if the personification of Sheogorath wills something, then his power trumps Haskill's. Unfortunately, this model then ignores Dyuus who was Jyggalag's Haskill, but as I said, the theory's incomplete.

Interesting..so you believe a Daedric Prince's sphere needs a small Anuic sustainer in order to prevent completely dissolving in all directions? It makes sense, in a way. It might even be argued that without Daedric influences, even subtle ones, the Mundus would remain more or less unchanged. It seems like the two need each other - stasis becomes meaningless without change and vice versa.

The chamberlain position is that of a mnemonic crutch, which fits what you said, Mr. Dagon.

Well of course? Enantiomorph, anyone?