Can I send special keys or insert pauses in Snippets favorites?

Yes. The "Macro Snippets" are for users with some experience with scripting language. They allow you to send special keys to the active application (Tab, Alt-keys, Backspace, arrow keys, etc.) and special command to pause the snippet execution {&Sleep:n}, slow down its execution for better compatibility {&SetKeyDelay:n} and suspend the execution until a given key is pressed {&KeyWait:keyname}.

More info on this Snippets Help page.