#1 is the most complicated because you have to account for tense. Basically all it is is changing the verb into a noun-modifying (adjective) form and adding the word "thing" (것) after it. In fact, this is the way the future tense is formed.
ㄴ/은 - past tense
는 - present tense
ㄹ/을 - future tense
예) 공부하다
공부한 것 - the thing (I) studied
공부하는 것 - the thing (I) study/am studying
공부할 것 - the thing (I) will study
When you're just making a general "I like/dislike" statement, you use 는 것.
-> 저는 한국어를 공부하는 걸 좋아해요. I like studying Korean.
Since "studying Korean" is the object, you add 을 to 것. This can be contracted to 걸.
공부하는 것을 -> 공부하는 걸
-> 저는 책을 쓰는 거하고 티비를 보는 걸 좋아해요. I like writing books and watching TV.
것 -> 거; 것을 -> 걸; 하고/랑
Future tense:
-> 내일 저는 한국어를 공부할 거예요. I will study Korean tomorrow.
So you're saying "It's studying Korean I will do tomorrow."
Sorry this is a bit disorganized >.<If you have any questions let me know.
I'm not a native, by the way^^
You can use talktomeinkorean.com and howtostudykorean.com to reinforce, learn more, and practice.