1. In the first test I focused on responsive design, HTML5 and SASS and opted to code in pure JavaScript.
Works in IE9, is retina friendly and maintains core functionality even when JavaScript is disabled.
The result can be viewed here.

2. In the second test I focused on achieving a result with the minimal amount of code.
Pure JavaScript, no libs. Tested in IE9, iPad and Android.

The result can be viewed here.

3. All of the source code is available on GitHub: Git Repository

5. API Test: Image

6. Simple SCSS Media Queries: View on codepen.

7. Generating colour themes with SCSS: View on codepen.

8. jQuery Plugin using module pattern: View on codepen.

9. Experiment for indexing code snippets and Dev articles: View here.

10. Above experiment coded in a weekend using ES6 (Needs tidying but demonstrates import etc.): View on Github.

11. The most practical way for cross browser testing. A video on how to install VirtualBox: Installing a VM in under 9 minutes.