how long is lvl 80 story?
You can do the HoT story without finishing “core” personal story.
You can look up how long anything is on here:
https://wiki.guildwars2.com/wiki/Main_Page
or look up pretty much any information you are looking for. It is updated by the players so if you find something is not updated then either do it yourself or leave a comment in the discussion page about the needed fix.
As above you can skip rhe story if you want your elite.
If you are doing the story in order though, you are not far from the end of the core story arc. Then you have the video recap of the first living world season then you would purchase living world season 2 (8 episodes) then you have HoT.