Can contacting a search committee for questions about the position hurt your chances? Most job postings include an email (usually for the chair) to contact the committee's chair. I have so far never dared to use it for fear that i'd get sidelined for asking stupid questions. Things that I've wanted to ask in the past but haven't include:


Could I amend my application by adding document X (after deadline has passed)
Would you be interested in an applicant with a background in X and Y, having worked on Z (with CV attached)
Could I submit one more recommendation letter than the specified number?
Should the "Teaching statement" (or whatever they call it) include student evaluations (if they're not asked for anywhere else in the ad)? 


Could asking such questions potentially hurt a candidate's chances?
It is hard to be definitive here, but I don't think the questions you are suggesting will help and might hurt. They are questions about the "candidate" (i.e. you) not about the position. (See the last paragraph here, however.)

On the other hand, my opinion is that a true question about the position and the department in which it is being offered are appropriate. Questions like "Are there frequent/regular seminars attended by faculty and advanced students?" Or: "Do students have an opportunity for independent study and do they take advantage of it?" Here you are asking about the environment of the job itself. 

If you have to ask the questions you list, it would be better (opinion again) if you ask them of some higher level authority than the hiring department or the chair of the committee. 

However, if a problem arises in your application in which you have a serious need to know the answer, then, yes, ask it. If you already have a problem then you need a resolution.