When will one be able to How do you say "When will I be able to go to China?"

After trying to figure out and failed, I tried to translate the sentence from Korean to Chinese and came up with this :
"什么时候能去中国?"

Now, the questions are:


Is that correct?
Why is there no question marker (such as 吗) in the translation? I wonder when I should use 吗...
When are we allowed to omit question marks?
And why is it using 能? Shouldn't it be using 会? Since 会 is more related to future possibility.
First, it is correct, yet not precise, it is supposed to be


  我什么时候能去中国？


Second and third, there is no question marker because "什么" already implied that this is a question, you would use "吗" when it is not obvious if the sentence is a question


  我能去中国吗？


Last, "能" corresponds to "able" in original expression. You use "会" for possibility, like


  他什么时候会去中国？


This means "when will he go to China?".