Can you tell me what I would go to HR for, and what can be addressed by my Department Chair?

The departments you may interface with from time to time are as follows:
 

Human Resources: Benefits, Payroll, Workman’s Compensation

Faculty Affairs: Academic Personnel, Labor Relations & Collective Bargaining, Retention, Tenure, and Promotion (RTP)

Department Chairs:  Department Budget and Faculty Affairs

Sometimes your question can be answered by the Department Chair and the Assistant in the office, but generally, the responsibilities are categorized as shown above.

If your question involves support to attend a meeting, eligibility for a grant, or something of that nature, check with the Deaprtment Chair.