Location depends on your discussion section.
Problems will be similar to those on the HW and discussion worksheets. Some will be straight computations, others will be conceptual short answer questions, and others multiple choice or true/false questions. Taken collectively, the HW should be viewed as constituting a study guide for this exam.
Working additional problems from the text is the recommended way to prepare for the exam, as is doing the problems from the worksheets that you didn't get to in section. A key resource is the excellent list of review problems at the end of each chapter, including quick concept checks and a true/false quiz. For Chapter 12, all of them relevant. For Chapter 14, what we've covered is reviewed in:
Additionally, in WebAssign you will find assignments titled "Review 12.1" and similar. These contain all the WebAssign problems corresponding to that section of the textbook; while they are essentially copied over from the textbook, they have the advantage of giving you access to the solutions.
Here are some old exams whose authors overlap with those writting the exams for this semester, with solutions. Important Note: In section on Thursday, Sept 19, you will take the 2012 exam in timed conditions as practice, so you don't want to look at it before that (the practice exam won't be graded).
If you have a conflict with the exam time, please consult the university policy on evening midterm exams. Based on that, if you think your situation qualifies you to take the conflict exam, please fill out this webform at least one week before the exam date. The conflict exam will be held Wednesday, Sept 25 from 7:45–8:55am in 314 Altgeld (note that is in the morning, not the evening).