Don't panic. Many petitioners could receive RFEs from USCIS, and there are many successful cases.

While the adjudicator of your case could raise some specific issues for you to response, the focus of almost all of the responses to RFEs are the same, that is, to readdress your academic excellence, your achievements and the significance thereof. Of course the emphasis for EB-1/1 and NIW is a little bit different. To do this, you will have to submit to the USCIS your newly published works, your new findings, and new testimonial letters from experts and authorities,etc.

A new coverletter is needed. But it does not need to be lengthy.

Good luck.