Writing Get old exams from TAs who have previously taught the course or from the course supervisor and use them as a guide. You may or may not provide a word list from which to pick words. Students certainly prefer to have a word list provided. If used, students won't know whether to look for choice starting with a vowel. Refer to the comment made above in the Matching Questions section.
Calculation problems Provide a place for students to write their answer.
When grading the exam, the blank allows you to quickly find the students' answers. It also forces them to declare a particular value as their answer. Provide a point value for each question. If you use multiple forms then at least two other issues become important. If don't tell them and they think that there is only one version they may be more inclined to cheat.