Can I just ask -
Some Robot Tags are set to:
Others are set to (including mine)
does this make a difference, if so, what is the difference and which one is best?
by default search engine spiders want more content...they usually think bigger is better (as long as they do not view the content as spam)
by default all search engines are set to "index, follow" without any tags
those tags do not really help your site at all. only use them if you want to prevent spiders from indexing or following, in which case you would use noindex, nofollow or both depending on your goal.
brief rundown of the meta tags worth using (title, descripton, keywords) and a meta tag generator here.
official robots meta tag page