Publishing App, cost and accessibility

Hi, I have questions regarding an app I am designing. One of the main feature of the is allowing users to interact with each other through the chat window.

Based on this, my first question is:

  1. Is there any way moderate the app e.g block users interaction through the chat window?

  2. The app is for an experiment, and we are expecting at least 400 users to constantly chat with each other for at least 3 months. Based on this, what is the subscription plan I should do to ensure seamless interaction (e.g. $56?)

  3. I want the app to be accessible both on Android and IOS, is there are guidelines on how to do that or any better alternatives to deliver the app to avoid extra cost?

Thank you so much and looking forward for your response

Welcome to the community :partying_face:

You can create that! : Help to get to delete an email in a text property - #4 by dilon_perera

Starter or Professional would be good!