1. generally considered the best buff, the druid's mark of the wild boosts armor at early ranks, and then also boosts all your stats later. so it boosts both mp and hp, but not egregiously. and even later, it boosts your resistances as well. at its final rank, motw, without the talent boost, increases your armor by 285, your attributes by 12, and your resistances by 30. it's an awesome buff, but by no means a swg buff or the like.
2. by level cap you will, if you can wear plate, be able to block a whole lot... of attacks from much lower levelled mobs/players. you still will get smacked down by the raid mobs you're going to be fighting. in wow, it seems, there will always be plenty of things that can school you.
3. blizzard has not commented on housing as of yet, as far as i know.
4. you get two primary professions. these are generally either farming or crafting, and most people couple two (they seem designed for such): you would pair herbalism with alchemy, mining with smithing or skinning with leatherworking (there are more, but i don't remember them). the crafted items you've just trained from the plain old trainers are sometimes extremely cool, but especially cool are the tradeskills you pick up off of a mob or a remote vendor. you can't craft like "THE BEST ARMOR IN THE GAME" but crafting is still useful. there are three secondary skills: fishing, first aid, and cooking. you can have all three, or you can have none. it doesn't really matter as much, and they're useful, but not as useful as your primary professions.
5. i think the latest word is that you get 8/server; if you're playing pvp, then you can only play one faction on any given server (you can't create a spy).
6. i ran into grinding really early on in eq2. what grinding there is in WoW is mitigated by the relatively high frequency of uncommons dropped, by any attending tradeskills you might be working on (like killing a creature to lvl both your skinning and, eventually, your leatherworking), and because there are quests that award some grinding (kill x amount of these creatures and recieve this reward). also, while a lot of mobs are just duped models, there is also a whole lot of subtle variations between the dupes, and, even better, the mobs that appear in a zone are usually quite unlike the mobs in the neihboring zones. plus... the game is generally beautiful to look at across every inch of the map. the first time you walk into any settlement, i bet you'll at least smile, if not draw in some breath in shock. just really nicely done, there, and that too releaves a lot of the pain in any grinding you might do. and even then, i got one character to levle 20 without grinding once. if lvling a druid from 28-29 costs like 34k experience, and the toughest mob you could bead gives you something like 180 exp, then grinding is hardly effiecent given that you can arrange quests by area, do all in one area (or most, anyway) and recieve 900-4k for each one.
i've never played swg, but have heard little good said about it. can't help you there.