GTV Exceptional promise Arts Council/ media review content

Hi everyone, hope you are all doing fine! I am preparing my documents to apply for stage 1, endorsement as a visual artist.

I was wondering if anyone here that has applied under this category had a successful result, and if so, how long was the review of your work in the media recognition? How long should it be? would a small paragraph be enough?

Another thing, I want to use invitation letters from international organizations who invited me to take part in their events as proof of appearance, do the invitation letters need to have an official seal from government authorities? Do you know?

Hope someone can help me with these questions, I am so nervous and insecure about sending this as evidence, thank you in advance for taking the time to read my questions!