People have already stopped using the B/G deck online for the most part, except the ones that actually want to play it. During the first week, when no one was playing tactically or had cards unlocked, B/G was overpowered; now it's just like all the others. Been playing a lot with the Black/Red deck lately, but it's important to note that all the decks are overpowered in their own way--they all have unlockable cards that are downright scary.
I would say yes. The How To Play section is pretty detailed and the tutorial teaches you the basics very well. The challenges (now integrated as optional parts of the campaign) will introduce more advanced concepts, but they start with baby steps.
There seems to be a lot of the site that doesn't play well with IE9. Quest pop-ups never load, commenting is pretty broken, wiki editing is a nightmare, the layout suffers a bit, chat room doesn't work, obviously Theater mode doesn't work. I guess I have to start Chrome every time I want to visit Whiskey sites.