I can't get channel editors by using bot irc commands - authentication failed

I’m trying to figure out how to get the right token with documentation article that you sent me.
But there are a few questions that I do not understand.
I’m using the V5 API.

  1. What should I write in the grant_type parameter, the documentation says “This must be client credentials”, but what are these “client credentials”?
  2. Why, in the example, the token lifetime is 3600 seconds, whereas the above App access token description says " App access tokens expire after about 60 days"
  3. I didn’t quite understand the scopes specified in the https://dev.twitch.tv/docs/authentication/#scopes
    The following features are required for my bot:
    a. To connect to different channels
    b. To be able to read messages in these channels (to receive commands from users)
    c. To be able to get the channel id by channel name (in order to execute command of enabling bot in channel)
    d. To be able to get a list of channel editors by channel id (in order to be able to determine whether this user has the rights to initiate the work of the bot in the channel, so that the random user could not add the bot to the channel)
    e. Be able to send whisper to users (in response to their commands)
    f. Get the user id by username and get the user by user id to find it in our database, to execute the commands requested by them.
    What scopes should I connect to be able to perform all these actions using the API v5?

I do not know how it is accepted in Twitch, whether it is necessary to check at the user who wants to connect a bot to the channel, the rights of the editor of the channel or not?