That will work for any URL of the form example.com/node/whatever, but it won't work for example.com/something/node/whatever ... is that a problem?
I have read somewhere - I no longer have any idea where - that Google likes to be addressed personally, so you write one version for Google and one for everybody else. e.g.
# For Googlebot
# For all bots
I've no idea how reliable that information is, but for the sake of a few bytes, it does no harm to include it. It works for me.
I've not seen anything like that. What you can do is to give Googlebot (or any other bot) different restrictions by specifying those first and then doing a catch-all * for 'all others'.