Are these correct?

1. Ben etle yag yerim. (I eat meat with oil.)

2. Komiksin düşünüyorum.

3. Komiksin, düşünüyorum.

4. Komiksin. Düşünüyorum.

I think 2. is wrong but I´m just checking. If I said Komiksin düşünüyorum but I paused in between the 2 words, would that sound OK?

This sounds strange to me in English, because I´m not sure what you want to say.

yağ = oil / fat

You eat meat cooked in oil (ie olive oil)

You eat fatty meat. (Yağlı et yerin.)

I eat lean meat. (Yağsız et yerim.)

My thoughts (as a learner) on the second part of your question:

Komiksin (if you said this by itself, then I think it is obvious that this is what you were thinking)

or if you wanted it in a sentence:

Sen komik olduğunu düşünüyorum.

etle yağ yerim may be

I eat fat with meat

I eat fat and meat

"ile" can be trasnlated as "with" or "and"

2. sounds strange but can be fixed this way

komiksin diye düşünüyorum = I think you are funny

Are these both correct? Which is better?

Hiç oraya gitmedin mi?

Hiç oraya gittin mi?

Also, I saw this: Tom şanslı idi. 

When can we use idi/idem -

or is this uncommon?

Is it onların için or onlar için or

both are OK? 

Thankyou!