... menus, sites and module repository. Each of subsites can have own database data, but note that you use same Joomla installation, so all files are shared (files are same for all sites). Depending on subsite user's permissions they can change files and affect other sites, so you need to limit certain ...

Yes, single Joomla installation is better for you, in this case all files including images will be also shared, so you won't have problems with avatars. Note that MightySites shares database data only, not images. Using different installation will create additional problems, ...

... permissions. In this case you can create separate Admin usergroup for each site and setup permissions (permissions are unique per site and not shared) to allow only users from site's admin group to login to backend.

... of main site. That's not possible and www.secondary.com should use same Joomla installation as main site, in this case files and images will be shared and you will be able to use these extensions properly. Besides MightySites doesn't allow virtual sites like www.secondary.com/newsite, only domain ...

... handle this? 2) Will I be able to easily replicate/create a new site when they open new facilities? 3) While all content categories are shared, I would assume that I could still designate users that could only affect certain categories, and add content only to those categories on the ...

... from FieldsAttach Possible, subsite can have either own menus or own articles or you can implicitely setup a different homepage (even if menus are shared from other site). - Each sub site needs different template style/variation which will include a different menu selected from the template variation ...

It will work as usual if data is not shared.
For sharing support of data please create a ticket in our Support Center and attach extension.

In this case EasyBlog data can be shared.

... the templates are uploaded along with j3 and content to a site's empty root folder. I want to lower my inode usage from my hosting company by shared use of joomla 3 for these sites, do you think that I can do this. I would have to some how configure MightySites then delete the two joomla installations. ...

... would like to share all of the articles and content but also would like to be able to create content for individual sub domains which would not be shared, this is because each sub domain services a different geographical area and there is a need to localise some content. Is that possible? If not ...