Omniscient narrator point of view.
Does the author use point of view primarily to reveal or conceal?
I would say that the author uses point of view mainly to reveal information and personalities not conceal them.
Is any of the characters a developing character?
Ivan is certainly developing character
If so, is his change a large or a small one?
It happens gradually but still it seems a slightly dramatic change from a cordial fellow to a deathly depressed man.
Is it a plausible change for him?
I think the change found in Ivan’s character is definitely plausible.
Is it sufficiently motivated? Is it given sufficient time?
Well to move the story along this change in Ivan is needed and I feel that it is done within sufficient time. The whole book moves through things quite quickly though….