The documentation for Windows Manifests is
here and, yes, it's poorly documented.
A couple of things I can answer...
1) the PublicKeyToken in DependentAssembly is the public token of the windows common controls DLL. Thus it should always be...
publicKeyToken="6595b64144ccf1df"2) ProcessorArchitecture has to match the code... for 64bit code use "amd64" for 32 bit code use "x86."
3) The execution level setting is about the Vista/Win7 User Account Control --that stupid nagging "do you want to allow this" window people absolutely hated in Vista. Basically it sets the level at which your program will operate within the system... known values are "AsInvoker" (same as user), "HighestAvailable" (as Admin if availble, AsInvoker if not), "RequireAdministrator" (pops up a window saying "you need permission...")... The most common level is "AsInvoker". If this is not present, the Vista UAC will ask if you wish to allow the program, *every time* it is run.
4) The compatibility settings are about running the software in a "compatibility environment"... for example running older software in an environment that resembles Windos XP... the OS ID tokens identify the various operating system versions and should be copied exactly. Generally this section is not needed unless you are updating some seriously old code.
5) the DPIAware setting is either True or False... Starting with Windows 7 you can use CTRL+MouseWheel to zoom some applications text larger and smaller, you can also set the Dots Per Inch of the display and windows will resize automatically... The DPIAware setting enables mouse wheel zooming.
Code signing is documented
here and once again it's rather sketchy.
My understanding of this is rather poor, so please forgive any errors... The basic concept is that you acquire a certificate from a third party that is accessible online when your program runs... the hashed checksum of the code on your system is compared with that stored in the database, if they don't match you will get a certificate error and the code will not run. This is not a free thing, certificate agencies (VeriSign for example) charge thousands of dollars to issue an application certificate. Currently code signing is optional but under the new AppStore paradigm it may become necessary to have digital certificates before you can list with the AppStore. (And YES... I do happen to think this is a very stupid way of doing things that stifles creativity and pretty much puts the average Shareware or Freeware developer out of business.)
Hope this helps...
I'm attaching the manifests I commonly use in my projects...