You should have received an email and a message with more info in Creator Studio, including detailed resources and next steps. Note: if you were removed from YPP for policy reasons, you can always reapply in 30 days.
There shouldn't be any issues with making archived live streams private. But if you're looking to monetize, it's best to make videos public to get more views and revenue. More info here: https://yt.be/help/bKTm . Hope this clarifies!