Originally Posted by
Poppincaps
I'm kinda in the same boat as you so I'll try to give you some answers.
1. The only expansions with real story relevant content are Rise of the Hutt Cartel and Shadow of Revan. The others are just fun side stuff.
2. Yes, Shadow of Revan has 2 new worlds with a 3rd added in a recent patch that all have story content.
3. If you want to reach level 60, then yes you need to buy Shadow of Revan, but keep in mind that you get the new expansion and all previous expansions when you sub when the new Expac launches. So you can pay the 20 dollars for SoR now or wait a month.
4. As for the lore you can either do all the flashpoints or watch videos on them. From what I've heard the Ops are mostly their own side story type thing and don't really deal with what happens in the main story. But you should be able to find Youtube videos of the Ops and Flashpoints to give you the lore you need.
I'd recommend that you sub (you'll get the expac a week early) and level some new characters with the 12x xp. You can also get your main to level 55, although if you're 53 and already finished the main story of RotHC then I don't know where you should pick back up. I've been using this time to play all the side quests and class missions on my Jedi Knight and then I plan on running through the class stories of all the other classes with 12x XP.