1.) The buzzard nerf effectively killed the hunter class in my and others' opinions. Since buzzard is the only reliable form of draw that a hunter can make use of, its absence in a deck means that said deck is inherently weaker than those that include it. However, this nerf is just too scathing. At 5 mana, it is unplayable. You can't play it a turn in advance to set up a combo, because the 2 health is easily dealt with, nor can you play it the same turn as something else and get good value out of the combo. The result of all this is that Hunter is pretty much non-viable at most ranks. I managed to put together a trap hunter deck which does well enough, but I can't imagine getting to legendary with Hunter any more.
2.) I didn't have one, and regarding the nerf, same as above, only the Leeroy nerf didn't screw a class over. Leeroy now is essentially a worse Reckless Rocketeer, an already bad card, only it gives the other guy minions as well as being inefficient at 5 mana. It is basically unplayable, though the decks that ran it have mostly recovered, with miracle rogue adopting Malygos, and handlock throwing in
JARAXXUS, EREDAR LORD OF THE BURNING LEGION.
3.) More cards are needed, post-haste. The Naxx cards were a good start, and the meta was shaken up a fair bit, but a proper 100+ card expansion is required at this point to keep the game from becoming irreparably stagnant.
4.) Quite good, all things considered. I've gotten much better at Arena, even getting my second 12-2 win with Priest (first time was with Paladin). I collect dailies regularly in unranked, because I have no interest in grinding to get to legendary. My decks work pretty well overall.
However, the meta is pretty unremarkable at this point in time. Zoo is rampant, handlock's making a comeback, miracle went spell power, and control warrior is as frustrating as ever. Also, as one of those weirdos who plays the game entirely F2P (I've never sunk a single cent into it), it's difficult to netdeck, because it's so damned expensive to craft cards. I have, what, 6 legendaries I think: Black Knight, Jaraxxus, Krush, Tinkmaster, Ragnaros and the Beast. Only Rag fits into current decks, and even then, not on his own. If I want to keep up with the meta, I'd need Alexstraza, Grommash, Tirion, Cairne, maybe Thalnos and Sylvanas, just to name a few. To craft all these, I'd need 9600 dust. Regular card packs give around 60 dust each, which translates to 160 card packs, or 16000 gold or 107 arena runs to make. By the time I'm able to acquire all this, the meta will undoubtedly change, either due to an expansion or a new combo which no one can match, rendering my effort moot. Keeping up with the current meta is not for me, as it's just not worth it for the level of play I most enjoy (Arena).