1) First risk is that avast is bad Anti-Virus protects against viruses. Though, I recommend other Anti-Virus like Avira Antivirus Personal is free version of Avira anti-virus database that gives anti-virus and anti-spyware safety against unsafe viruses, worms, Trojans, malware, spyware and dialers expensive. It is good and free, but it always pops up and shows irritating nag screen which advertisement convinces users to upgrade to paid premium edition of Avira product.

2) These infections are projected only to show pop ups alerting to download and install rogue. Occasionally, rogue is added in infection and is installed without knowledge. Generally, scan begins rogue only, rogue will detect many infections more or less unreal but always scan window tells you that you must pay to clean PC. As you have understood, aim is to make you purchase fake antispyware simulating infections.