Can I read AssemblyFile information in Inno Setup

Use the GetStringFileInfo() function provided by the Inno Setup Preprocessor (ISPP) as follows:

1. GetStringFileInfo("path/to/greatapp.exe", "CompanyName")
2. GetStringFileInfo("path/to/greatapp.exe", "ProductName")
3. GetStringFileInfo("path/to/greatapp.exe", "FileVersion")

As you have already mentioned, you can use the GetFileVersion() function instead of #3 above.

Also, have a look at the ISPPBuiltins.iss script file included with your Inno Setup installation. It contains a GetFileCompany() function to use instead of #1 above and you can implement #2 above in a similar fashion.