As far as I know, there is only one time to add whatever search keys or tags you think might help other people find the posts you make - that is on the original 'new thread' screen. There does not appear any other place where they can be added or edited - maybe it's a moderators task ?

Secondly, for some reason I don't have access to the image smiley's and other such icons that would lighten what I have to say. Again is this deliberate ?

Every thread may have up to 8 tags total. Up to 4 can be given by the thread starter and the rest by other users.

I just added two tags to this thread by clicking on the "Edit tags" link right above the quick reply box.

As for the smilies, those can be added at all times but if you want the clickable menu you need to use the full reply screen rather than post through the quick reply box.