As the documentation notes, the "{GUID}" token generates a random GUID.
Press F1 while VoiceAttack has focus to open VoiceAttackHelp.pdf in your default PDF viewer, which contains information on VoiceAttack's features.
To retrieve niche information like that, you'd need to write an inline function.
Wildcard commands are technically possible when using the SAPI speech recognition system, however the words used would need to be present in the Microsoft speech recognition dictionary.
If you're looking to speak the name of a running process or a window title (or other information that can be used to build predefined phrases), you could use the "Wait For Spoken Response" action instead.