Last year I had a bit more leeway (sp?) and since we could list unlimited post-secondary experiences, I listed each thing separately (once for poster presentation, once for abstract, once for attending conference) and then reference the other things in my paragraph.
I realize you are much limited this year, and you should try to roll all of these experiences into one experience. So, my take on it is if you attended a conference/presented a poster/authored an abstract, you should list all related experiences under posters/presentation, but then in your paragraph, list that you also attended such-and-such conference and authored the abstract for the poster.
The format you listed is what I used last year, but I also included other info, like co-authors, awards won at the poster session, travel awards won to attend the conference, the abstract info, etc.
I hope this helps.
Good luck! :wink: