Pretty sure any assignment to the NSC is 'At the pleasure of the President,' or at least one of his appointees. Escorting someone out of a high security area is pretty SOP, but he deserved it particularly as clearly any trust placed in him has been broken beyond repair.
Promotion to a higher grade?!? For someone who is just a Foreign Area Officer with no command time, it's a miracle he made O5. It is extremely hard to make O6 and the chances of the Senate approving any promotion list he showed up on (If that miracle happened) are the the ultimate longshot.
This is just my conjecture, but everything I've seen about Yovanovich is that she was working much more in Russia's interest than Ukraine's, though possibly her loyalty to Obama and Clinton (NOT the USA) outweighed her Russian priority. Her ass should have been fired when Trump came into office three years back. It appears to me that she and Vindman, along with others, were involved in their own little cabal that was not pursuing the best interests of the USA, Ukraine, or Donald J. Trump.