Answer 1

Look into Kali. You can then use aircrack and a selection of other tools to brute force the password. Also you can use something called reaver which I really like as this doesn't rely on a password list. Youtube is overloaded with these wifi cracking videos for kali, but don't just follow the video, make sure you understand what they are doing and why otherwise you won't ever understand the processes and how to make your wifi more secure.