After reading around I have confirmation that myself as a non-resident alien living abroad married to a US citizen living abroad do not need to fill in US tax (I can "chose" not to).
However, for my wife 1040 declaration, she will be choosing the "married filling separately" option.
But then, does she need to leave the "Enter Spouse SSN above and full name here" and "Spouse Social Security Number" boxes empty?
Also, I believe I read she should tick 6b in Exemptions, is that because I am not filling? Is there anything else required to cover this issue on the 1040?

If you are a non-resident alien with no US-source income, your spouse can take an exemption for you.
You would need to apply for an ITIN using form W7.