No, it is not possible to designate a parent at project creation wizard, it must be manually selected. Adding a parent project just puts it at the top as a peer to the others so your second question is a little confusing.
A template is a snapshot of a living project so if you go into any project (any parent or child of any type) and select "Create Template" from the menu it will appear in the templates area. You should see all of them under the Templates tab.