Actually it would have. Oil is a fungible commodity. It would have reduced oil importation from overseas suppliers, including Russia.
No, again, it would not have. The intent of the Keystone pipeline was to increase production for export to othet countries. Meaning it would not be oil consumed by Americans.
Renewables are a red herring to the question. The case for renewables is valid regardless from whence our current oil is supplied. The point is does the US want its oil coming from Canada or Russia.
If we reduce our need for oil overall, how is that not relevant to oil imports? Obviously it's relevant.