Secondly, forget about WiX for now. Your concern is Windows Installer - WiX is simply a tool to define Windows Installer databases (MSI files). WiX is no different than many other products out there, except for the fact that it doesn't try to mask any Windows Installer concepts for you. InstallShield transparently does a bunch of things that Windows Installer doesn't support via custom actions and the like, WiX forces you to think more about the Windows Installer methodology and way of doing stuff. Windows Installer is what you want to understand, WiX comes afterwards.
Second, get a copy of The Definitive Guide to Windows Installer. This book is an invaluable resource for anyone looking to understand how Windows Installer (MSI) works.
Firstly if you start with the first entry in the UAC in MSI blog posts and you should be able to get a better grip on things. Best thing I ever read in trying to understand the elevation, permissions, etc.
Third, start with the first entry in the UAC in MSI blog posts and you should be able to get a better grip on things. Best documentation I ever read in trying to understand elevation, permissions and all the other stuff that goes with UAC.
The image kind of makes sense, but I think think the UAC series describes the sequences a bit better. Very few people use administrative installs, and if your installer is written properly then there shouldn't be any reason to concern yourself with Advertised installations either. They'll just work. Build your installation to work with only the InstallExecuteSequence to begin with, and then add the UI later and you'll have a bulletproof installation that works without much effort.