2 questions regarding Atlas: Can I not specify which database/cluster a project level user can access? Also, is it possible to specify replicationfactor within the Atlas UI?

I’m just getting started with MongoDB Atlas, and I have a couple of questions that I haven’t found an answer for browsing through UI/Docs.

First, I keep reading that I can scale the cluster, modify replicationfactor, but I can’t find any settings like that when setting up an instance, but I see it can be specified at cluster creation time, using the API. Nor can I edit the cluster to change it. Is it specific to a certain tier? I’m focused on dedicated tiers, currently, but have started with an M10 to start, though I expect that to grow as we continue on the project.

Second, regarding permissions. It looks like there are two layers of user access within a project. One is at the Atlas project level, the other is at the Database Access level. The latter, I assume, only allowing access to the DB and not Atlas. Database Access configuration allows me to specify which cluster/DB the user can access (same for Data API).

But, when I assign permissions to an org level user within a project, it doesn’t appear that I can specify which database they can write to. So, it seems the only way to get that separation would be to create a separate project.

My usecase here is to have a project dedicated to a team, and houses prod and non-prod clusters. I want to grant my users access to the Atlas project, so they can have visibility into various aspects of the project (beyond the DB), but only certain people should be able to write/admin certain instances that way.

Thanks for any suggestions or clarification. Hopefully, these questions have enough context.