How to know the storage utilization per project

Dear all,

I have almost 50+ projects created in my Redmine setup and I have almost 400+ users.
My users finding slowness in the system and to mitigate this issue I want to know the following information:

1. How to know how much storage is utilized by each project?
2. How to know how many users are logged in at the same time?
3. Do we have a common setup diagram for Redmine environment?