I have created an application and implemented Firebase (Auth, Analytics, Remote Config, Crash Reporting) with it.
Now i need to change the Firebase account because in my collaborator account we will implement Realtime Database with BLAZE plan. (we need more than 100 concurrent connections to db)
1- Yes, it's possible and you can follow this tutorial to do so.
2- If you want to simply switch projects, generate a new JSON on the console and remove the old one. If you want to migrate your database, it's possible, just check this question.
3- Both answers are "yes" so, try them out.