1: Never
2: Number 1
3:Also see Number 1
4: Visiting malicious Websites or open nasty Mails

Before i used Avast, i had AVG, before i had my own Computer we had Norton, but the computer of my Grandpa got infected
with 3 Trojans, then we switched to Avg, as AVG was slowing down my system i switched to Avast, the others are still using AVG and my
Uncle uses Malwarebytes Pro with AVG.