Answer to Question 1
Answer: The direct approach is favored for most routine business communications, as audiences will become impatient if they don't know why you are communicating with them and how the details support your message. However, if you need to persuade the audience to agree with you, or communicate negative news to people who will not expect it, or when the main point is so complicated that you need to build up to it, the indirect approach can be useful.
Some situations in which the indirect approach would be appropriate include:
trying to get your boss to give you vacation time during a busy season in your office
telling an employee that you cannot give him/her a raise, promotion, etc.
trying to get your department to implement some new policies
refusing a coworker's request for help on a project
Answer to Question 2
Answer: There is no one set of conditions that are best for everyone. Some prefer a quiet location with as few distractions as possible. Some avoid answering the phone or checking email while they work. Some focus better with music on while it makes it harder for others to concentrate. Some even thrive in the bustle of a lively caf. The key is to find the environment that is comfortable for you and then do your best to create those conditions while you work. Structuring your time is also an important consideration. First determine how much time you need to compose and how you can schedule that time between now and your deadline. Working a few hours a day, as opposed to cramming all your writing time into a short span does have benefits. Doing so will help ensure finishing on schedule, with enough time for evaluating and revising your message as necessary. It also provides the advantage of clearing your head and getting new perspectives between writing sessions, which can improve the quality of your writing.