There is code for warden scanners all over the place. The following open source scanner is from 2012 but it is still valid and very informative if you know what you are doing. And no Warden is not scanning outside of the WoW process. [Tool] EverScan - An Open Source Warden Scanner
Not anymore that HB triggers AV and firewalls. Anyway, everyone here can rest assured that we are monitoring Warden and WoW itself closely for any attempts at detection.
Blizzard does not need reasons to ban you. Even if they did, they could ban you on the spot and they never needed a reason telling you why. We are accepted, to limmitations. Communtiy complains, blizzard acts. Major communtiy complain = banwave. We didnt have a lot of them. Maybe 1 or 2. But the forum where flooded then with complains. I wouldnt worry that much tbn.