It's an example of allusion, because it alludes to the language in the Emancipation Proclamation.
This expression means that you don’t have to make a decision right about a future problem. You should decide what to do about that problem when the problem is directly in front of you.
The first one is the correct way to use it, since it separates the parts of the sentence into fragments that can still be understood without changing the meaning of the entire sentence.
