creating an additional portal will not install an additional instance of DotNetNuke, both portals will use same code files, but data is kept completely separated, therefore they cannot share module contents, regardless of the domains they use, even if the one is a child in a subfolder of the other.

After you've read the guide and experimented with portal exporting and importing to ensure that it will work for you, go and look at this module http://www.freednnsite.com/ from Onyaktech.

Note that templates will let you have the modules ready to go on the page, but the modules generally still have to be configured for your users. Nothing will simply duplicate a portal with everything ready to go. Note also that configuring modules for use is pretty much guaranteed to be beyond the abilities of just about anyone who fits in an audience that such as system would be targeted at. Unless you want to leave your users in a mess then you will always have to do some work to make it work for them.

Rob