World-of-warcraft – What hit rating do I need as an undead hunter in PvP to be hitcapped

It sounds like you're looking for a restoration (healing) spec. The classes capable of healing are druid, monk, paladin, priest, and shaman. Racially there aren't a lot of significant differences, though specific races can only play certain classes. (Alliance races are listed below as well, though the original question was about Horde)

• Druid (Horde: tauren, troll; Alliance: night elf, worgen) - limited to leather armor; tree form (cooldown ability) increases healing throughput; good profession choices: skinning/leatherworking, herbalism/(inscription or alchemy), mining/jewelcrafting
• Monk (any except Horde: goblin; Alliance: worgen) - limited to leather armor; use brews and teas as the primary basis of skills; similar professions to druid (I've never played a monk healer, so can't really address the specifics...)
• Paladin (Horde: blood elf, tauren; Alliance: draenei, dwarf, human) - can train to use plate armor at level 40(?), limited to mail previously; some people think they are limited to single-target (tank) healing, but do have some raid utility too; professions: any of the combinations mentioned above, or mining/blacksmithing
• Priest (Horde: any except orc; Alliance: any) - limited to cloth armor; best professions: tailoring/enchanting or herbalism/alchemy
• Shaman (Horde: goblin, orc, pandaren, tauren, troll; Alliance: draenei, dwarf, pandaren) - can train to use mail armor at level 40, limited to leather previously; can also use shields; in addition to direct healing spells, also have totems that provide passive effects and healing; professions: similar to paladin

For all, you can learn first aid, cooking and fishing as secondary professions that will come in handy.

Note that resto is much easier to level as primary spec now that you get access to the LFD tool at level 15. And, they're in big enough demand that you shouldn't normally have queue times that are very long.

ETA: Cataclysm/Mists updates

If you're not min-maxing at the level cap, your best bet will generally be at least one, if not two, of the three Gathering professions, Skinning, Mining, and Herbalism. If you do decide to take a crafting profession, choose the gathering profession that meshes most closely with it (i.e., if you take Leatherworking, grab Skinning, Engineering, grab Mining, or Alchemy or Inscription, take Herbalism.)

If you want to make money using a crafting profession, the best choice before the cap will be Inscription, as the Glyphs you can produce as early as level 5 will be used even by level 80 characters, providing you with a constant market.

If you want to produce things you yourself will use on a regular basis, Engineering provides fun toys, and trinkets at much lower levels than they'll be availiable as drops. Leatherworking allows you to make your own armor, but drops and quest rewards will, for the most part, be better than what you can craft - at least until the Cataclysm expansion releases. Alchemy will allow you to make a variety of useful consumables, but in general, you will have to make many more than you'll be able to use as you level, and there won't be much of a market for what you craft.

Enchanting is a viable option as well, and you'll be able to enchant your own gear as you level, which is handy.

Realistically, until the +Stat bonuses at 400+ skill come into play, there really isn't a 'best' or 'most useful' profession. There are a few that will be much less useful to you as a hunter, such as Blacksmithing and Tailoring, but for the most part, you should be fine picking out whatever you find fun.

The only other major note worth making is that each of the three gathering professions provides a free 'passive' boost as well. Mining will give you some extra Stamina for free, Skinning will give your character increased critical strike chance, and Herbalism will teach you Lifeblood, a free Heal-Over-Time spell you can cast on yourself on a short cooldown. The crit from Skinning especially should be very handy for a low level hunter, though the other two perks are nothing to sneeze at either.