Proper multi-db expectations

I have been watching this forum for a few months as well as reading the installation and use instructions. It seems that I should have a lot more confidence in this by now, but because of all of the forum posts with problems, I finally decided to hire someone to do this for me. However, it seems that it is confusing to everyone.

Since we want to provide a free blogging platform, we thought it best to start with the 4,096 configuration. My understanding is the plugin provides automation to creating and establishing the DB. Yet I am being told by experts after they read the instructions that there is still a major manual aspect to the set-up. Please clarify what is handled by the plug in and what is still required to do manually. For example, many people have reported the need to manually set-up the user_name and password for all of the new DBs. Is this true or does the plug-in do this?

Also, once this is all set-up, does the operation of adding new sites within the multi-site change in any way; in other words, does the allocation to the databases occur automatically? Or is there something else that needs to be set up at the blog level. I’ve probably read too many of the problems people have had and I want to make sure I really understand what the plugin does and what is still needed to make it all work.