When I first started out with WordPress I didn’t understand how templates were made. The learning curve is quite steep till you play around with the software by breaking and fixing it. I really recommend that you do this as it is probably the best was of learning the program. That being said it also helps to have someone around that can give you the basics right up front. When people are starting out I tell them to copy the wordpress theme file located in ./wp-content/themes/Default and copy them to something like ./wp-content/themes/TEST-THEME. This allows you to edit the files and if you mess up then you can easily copy the contents back in the structure and restart things. For the most part page.php, single.php etc… will normally all look very similar because most people want a consistent theme accross their site. Back and Forth arrows would most likely be on “post pages” to navigate between the blog posts but doesn’t make sense to have on content managment pages.
This file as you would assume is the theme file for any post that is labeled a page. It does not include posts, search page etc.
This file is called when ever you are wanting to see a single post. This differs from say when you open the blog where you might have several posts on the screen.