I noticed some quests have disappeared. for example the quest on tython where you can either help these padawans who are in love or tell on them and get them in trouble. But the quest isnt there anymore. the characters are still there but i cant find where to get the quest!

They didn't actually remove them. Just go to your map screen and enable exploration quests on the top right. The devs hid them because they're no longer necessary to level due to the increased XP reward from class quest and main planet stories.

Try opening your map and in the top right corner you should be able to toggle on or off "show exploration missions". So just make sure it is on.

It should return the exploration quests but yeah sadly some quest content got removed like breadcrumb quests for operations and bonus and the ending content of Heroic quests.

 

I really don't know the reason as Bioware haven't given one, only many people want them back. If you're interested a thread about it is here http://www.swtor.com/community/showthread.php?t=845833

When KotFE was released, some of the bonus elements of certain quests were removed or drastically reduced, so technically some have been "removed" because instead of getting a "Bonus stage 1, 2, 3 and final stage" to go along with a particular quest, you now get a vanilla "Bonus stage", and one or two of those Bonuses have been removed completely.

However, as others have pointed out, the quest relating to Moracen and Spanios is now classed as an "Exploration Mission" and is hidden by default, so you can skip it if you want to just do enough quests to keep you leveled appropriately for the class story content.

Or if you are an OCD nut like me, you re-enable the "Show Exploration Missions", do every mission, outlevel the content and get to level 65 before getting your class ship at the end of Coruscant, and then complain that everything is easy

There's also some quests that some think were removed but were relocated, like the one with the Revanites on Dromond Kaas. The quest giver used to be near the central city taxi but was moved down to The Wall encampment.

Ah, I almost forgot about this.

That might explain why I never got a "Kill X amount of Cathar" quest on Taris and had to put up with Thana's boasting, and why the bonus quest-chain-giver on Balmorra wouldn't talk to me!