To avoid UAC prompts for applications on launch, there exists a manifest file which contains key information on the privileges. Many times, these manifest files are present along with the executable in the same directory. For example: Altair.exe will have a manifest file called Altair.exe.manifest in the same directory. There can also be cases where the manifest is embedded in the exe itself.
Here's a beautiful link on "how to interpret Windows Installer logs". This is a very essential and a noteworthy bookmark for every packager and administrator.
Here's a great reference if you want/need to learn some Windows Installer concepts and best practices. This document is very useful to individuals who are starting to do application packaging using Wise Package Studio.
The internal version number for Windows Vista is 6.0. The GetVersion function returns this version number. The problem is, some applications will return a higher version number. This means trouble. Learn how to steer clear, here.