Ok, there are a few things that need to be covered here.
First, let's address the membership of your Meeting Host Group.
Depending on your licensing, you may or may not have a limitation on this group. If you purchased the Named Organizer licens model, then you will only be able to put the number of people you have licenses for in that group (take 5 for example). These five indiviuals will be able to create and host meetings and must be present in a meeting room for it to function. You can assign meeting host rights to anyone else, so they can have that roll in the live meeting, but the member of the Meeting Host Group must be present in the room for it to work.
If you purchased the Concurrent Attendee license model, then you can put as many people in the Meeting Host Group as you want/need, and the limitation is on how many individuals you can have concurrently in meetings at any give time. With this licensing model you can create a room, asign host rights to an individual and let them run the room on their own.
For the folders, the difference between the User Meetings folders and the Shared Meetings folder is a matter of management. The access to and function of the room is not changed by where it lives on the server. What is affected is who has access to the server side functions of that meeting room. So if multiple people need to have access to the room (say you use it for weekley staff meetings) and there are a variaety of individuals who may be hosting the room, then it should live in the Shared Meetings folder (preferrably in a sub folder for organization) where all the individuals who may need access to the settings behind the scenes can get to it. Does that make sense?
Now, on to your questions:
1. Simply placing a meeting in their folder doesn't give them access to the management of it. They need to be assigned as a host of the room as well.
2. Assuming your licensing supports it, I would just creat the meeting in a folder within the Shared Meetings folder. You can create a folder structure in there to keep track of things in an organized fashion. However, if you are placing them in the Meeting Host group, so they can use the license for that session, it may just be better to put it in their folder and assign them host rights. Then if they need access to that room in the future, you just add them to the Meeting Host Group again, and the room should become available to them again.
The Date/time option for a meeting room allows you to schedule a meeting in your room using the internal calendar to the Adobe Connect application. This doesn't integrate with any external calendar system. It also has nothing to do with any creation of/deletion of/or access to the room. So in short, it does nothing, please ignore it.
The meeting room are persistant, meaning that when you create them, they can be available to you 24/7/365. This simplifies your work flow for using a room over and over, as it keeps a static URL and all of your content can live in your room, just waiting for you to access it. You are not expected to use the meeting scheduler for every meeting. I use Outlook and create a meeting request (with a recurrance if needed) and just include the URL to my room, as that is all my attendees will need.
Templates for the meetings is there so if you need to create multiple rooms, you can have a pre-defined arrangement of pods and layouts in the room that you like. That way when you create new rooms, you don't have to spend a bunch of time making it look and function the way you want.
Let me know if I missed anything.