Sarah,
Anyway is there a list of hash tags for list management that only
admins can apply to threads etc?
No. You create the hashtags at need.
Click on Hashtags in the left column of your group, then on the "Create Hashtag" button at the bottom of the hashtag list.
At the bottom is a list of checkboxes that you can use to give each hashtag the management functions you wish. The help page gives you a little more information about these functions:
/static/help#hashtagsI want to know in case I have to manage from the road and cannot
visit the site on my phone etc. an example might be if I want to
close a topic etc.
I don't think you can do add a hashtag to an existing topic, except through the web site (Edit Topic). So the example of closing a topic by email wouldn't work.
Shal