You have asked some very good questions, and it is understandable that you are eager to get closure on the hiring process. Interviewing for a new job can be one of the most stressful life events, particularly if you are unemployed. While you do have the ability to control your own behavior during the process, there are many factors that are out of your control. Realistically, the employer holds most of the cards.
For starters, it is not clear whether this firm will actually make a hire at this branch office. Deciding to add to your head count is a very difficult decision for any business. If their workload slows precipitously, the firm stands to lose profits. Similarly, if the firm decides not to make a hire and work increases, the firm will also lose profits.