Is a guardian limited on what they can tell the spouse or family member?

Curious as to why you are not your husband’s Guardian but no matter.
If you are not listed as a person that can legally get information then that limits what information can be relayed to you.
A guardian does have to appear in court to present to the judge an accounting of financial as well as how the Ward is doing. You could go to court.
You might want to consult your attorney to find out how much information you can get and how.

you sound like you are trying to entrap the guardian into something. They owe you nothing in response to your questions but perhaps if you actually converse you might find out some information you want.

Depends on the scope of the guardianship order, and especially on the scope of your questions.

Can you give us an idea what type of questions the guardian isn't answering?  

The fact that you want answers in writing suggests to me that there might already be some "issues" or friction with the guardian.  Is this the situation?