1. In the professional versions of DNS, using the Step-by-Step macro scripting is useful, easy to create, and is every bit as fast as any Advanced Scripting macro as long as it's used properly. For example, Type Text in combination with more than two or three command lines is not inefficient use of Step-by-Step macro and will cause them to execute significantly slower than Advanced Scripting macro. However, opening an application using a Step-by-Step macro is just as fast as any Advanced Scripting macro and almost as fast as opening an application by simply saying "open <application name>".

2. Step-by-Step macros are not particularly useful for opening an application by itself. They are useful for opening a specific document, such as a letterhead, and placing the cursor at a specific start location in such documents. The reason that there useful under this condition is that they not only execute quickly but they also open the document and position the cursor exactly where you want it to start dictating. There are other useful uses for Step-by-Step macros when you simply want to execute a small number of keystrokes sequentially using a single command. I could go on but that's something that you need to experiment with yourself.

3. When you initialize DNS and load your user profile, DNS goes out and maps all the applications on your desktop by application name, as well as any applications or application options in the Start menu | All Programs listing. However, when DNS maps all of these it maps them according to the text (verbatim) assigned to desktop shortcuts and or entries in the Start menu | All Programs listing. So, if you try to say open or start Microsoft Word, it won't work because that is not the verbatim text associated with either your desktop shortcut or what's listed in the Start menu | All Programs listing. Out-of-the-box in order to get Microsoft Word to load you have to use the exact (verbatim) wording. In the case of Microsoft Word 2007, you would have to say "open [start] Microsoft Office Word 2007" in order to open Microsoft Word. This is why Jomark recommends creating a shortcut on the desktop and renaming it to, and I suggest Microsoft Word rather than just "Word" because getting it to open might be problematic using just "Word" being that it is likely to conflict with other things that might execute in place of opening Microsoft Word. Nevertheless, if you do this and then say "open Microsoft Word", then Microsoft Word will open. This is perhaps the simplest of the approaches because no extra effort is required to write a script.

4. While you can also write an advanced script, as Jomark points out, that's a bit of reinventing the wheel and overkill to boot.  It's very effective and reliable, but do you want to write a script for every application that you want to open?  That would be a tad tedious, and why reinvent the wheel.  I would reserve this approach for situations where opening a specific application doesn't work using any of the other methods, and particularly creating and editing the text for a shortcut on the desktop, which is the absolute simplest approach.

The bottom line is use the simplest approach available without reinventing the wheel.  And use the other approaches where they are most useful and appropriate.