How/where to import Angular and Bootstrap .js files in my index.html?

I'm new to web front-end programming and am teaching myself AngularJS.

I have created a very simple webapp that just lets users login and logout. I am running it locally on my Mac OSX.

Below is my index.html file. Although it works, I'm not sure if I'm doing it right. I need to know how and where to import the angular.js files and the bootstrap.js files.

My questions are as follows. I haven't been able to figure this stuff out by googling. I need someone to explain this stuff to me please.

1. I'm currently importing the angular.js file from http://ift.tt/Q55qZD. Is that correct? Or should I download it and store that file in the same directory as index.html? Why? When should I use the non-minified file? What is the benefit of using non-minified?
2. I'm currently not importing any bootstrap file(s). Which file(s) should I import? Should I import it/them as a URL or as a file from the same directory as index.html
3. For both Bootstrap and AngularJS, please tell me which line numbers I should put the script src lines in my HTML.
4. Should I check the Angular and Bootstrap files into my Github repository?

index.html:

 1     <html ng-app="app">
 2       <head>
 3       </head>
 4       <body ng-controller="Main as main">
 5         <input type="text" ng-model="main.username" placeholder="username"><br>
 6         <input type="password" ng-model="main.password" placeholder="password"><br>
 7         <br>
 8         <button ng-click="main.login()" ng-hide="main.isAuthed()">Login</button>
 9         <button ng-click="main.logout()" ng-show="main.isAuthed()">Logout</button>
10         <br/>
11         {{main.message}}
12         <script src="http://ift.tt/1VpgoFJ"></script>
13         <script src="app.js"></script>
14       </body>
15     </html>

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