I was nominated right after my interview, in February 2010. And I didn't get my invitation until December 2010, to leave April 2011. In between nomination and invitation, they also ask for follow-ups in general. Most further information they need is related to medical and placement. The English Teaching Qs sounds to me like they want further info in order to place you well. How long ago was your nomination? Any follow-ups yet on the medical process? And online they should tell you how far you are in the process--if you have been medically cleared, etc.
Hope that helps!
RPCV, Botswana 2011-2013