My spouse is not a Canadian citizen/resident, so he does not have a SIN. How do I proceed with my tax return? It's requiring a SIN for him and other tax info.

You can enter 000 000 000 as his SIN number. Enter your spouse's net income from whatever country he is a resident of, but in Canadian dollars. 

Line 23400 less Line 23500 equals Line 23600. So, since your spouse didn't have any social benefit repayments, then Line 23400 is the same as Line 23600.