CES from IERF, still need from CGFNS CES for VSC?

No need for CES, but you have to submit to CGFNS all the requirements they need for VSC (Verification of licensure etc)

Definitely not. You're not going to do the CES for the Visa Screen, but it will look like you're going to the same procedure but with a lot of additional work, like English proficiency, NCLEX/CGFNS exam verification, etc. Just follow all the procedures and complete the requirements and you will be fine.

Good luck!