Hi, for the 1st , have you tried leveraging User Profiles?
Set a "User Created Date" Property: When a user first signs up, send a $set call to Mixpanel's API to add a "User Created Date" property to their profile.
Filter by "User Created Date": You can then filter users based on this property to identify those who were created within a specific time frame (e.g., new users this week).
OR
introduce an event like "new users" that records the user profiles/ ids per MIN (user created date)
then you just need to simply select that event, and count distinct the "new users" per month