Rating conversion
@1
Chess.com rapid rating is about 62 higher than FIDE classical rating.
Take an example:
https://www.chess.com/members/search?rating_type=rapid&rating_min=2200&rating_max=2500&coaches=0&streamers=0&titledMembers=1&sortBy=last_login_date
FM Santagati, Alessandro is rated 2315 rapid chess.com.
He is rated 2253 FIDE classical
https://ratings.fide.com/
That makes 2315 - 2253 = 62 rating difference.
You can refine by generating more such comparisons in the same way if you want.