> **1.** Android can only install `.apk` files (though `.apk` and `.zip` are interchangeable);

 >**2**. Yes, it does mean that, but you'll need a custom recovery which has the ability to flash .zip files. **Note** that such .zip files are not just applications packed in an archive, those .zip files are specifically designed for recovery flashing, and have specific scrpits that run when they are flashed;

> **3**. installing custom recovery requires root;

> **4**. As said before, you need root to have recovery so that you could install .zip files. To achieve root access, you'll need a PC.