Hi,
Yes. The Google Mini appliance will respect the robots.txt rules. You
are correct. The default user-agent that comes with the appliance is
"gsa-crawler". You may choose to use this string as is or change to
something else. It is up to you. More information about the robots.txt
file is explained here :
http://www.robotstxt.org/orig.html
Cheers,
Thiru