Hi,
Your questions are about standard Visual studio and it is best to use the Microsoft forum for questions about it.
The Visual Micro documentation is here
http://www.visualmicro.com/page/User-Guide.aspx?doc=index. It explains how to create and upload arduino projects.
Arduino has the concept of a "sketch book folder", this is where users are prompted to save program code when using the arduino ide. This folder is also the location where arduino libraries are installed. The standard visual micro menus direct new users to this arduino compatible process.
Now with that explained I will try to give you some answers to your questions ...
1) You see both 2005 and 2015 because sometime in the past you installed Visual Studio 2005
2) Visual Micro does also allows all the standard Visual Studio create/build commands to also build Arduino. This is useful for people who like the Visual Studio way of working. When using Visual Studio to create projects then the "Projects Location" box in your previous image is where projects are created and saved.
3) Visual Studio allows you to create project templates and item templates. You don't need to do this and should not change the default locations of these items until you know what you are doing. An example of an item template is when you add a new file to a project, such as .cpp file. You can extend the list of "new" files using "item templates" if you have common files or code you often create.
4) When you create a new projects you see a lot of different types of projects to create. These are "project templates". Users can export any project and make it a new project template.
5) A solution holds one or more projects. A project points to one of more source files. New users should work with single project solutions until they understand how things work.