phone interview for the position of Assistant Director of Public

I just got a chance of a phone interview for the position of Assistant Director of Public Works (water and wastewater) for a middle sized town with about 30 employees. Does anyone have any experience of phone interview in this occasion. Now the business is really tough, after working in consultant company for about 10 years, i really want to switch gear to work for government. This is a very good chance for me and i do not want to blow it off, but i do not have any interview experience and the current job i got was refereed by friend and interview was just a process.
1. normally, who will attend this phone interview, only HR or your direct report. how long will be interview be.
2. What are typical questions they will ask during interview
3. Anything else i need to be aware of