If you are on your first character, level 77 and you have to pay 1000g. If you are on an alt character, and have an 80, you can learn to fly as low as 68 with the tome of cold weather flight.
Northrend is a zone that you can get to at level 68 from Stormwind harbour or Menthill harbour on alliance
Dalaran is located in the sky of Crystalsong Forest in Northrend. If you are trying to get to it on your own, you have to wait until you are level 77 and have cold weather flying from a flying trainer, and are thus allowed to fly in Northrend, but you can also ask a Mage to port you there, or a Warlock to summon you there, you may do this at any level, but they usually ask for some money for it for the reagents required in their spell.
Gear for level 80s is dropped from Northrend heroic dungeons.
Not really you just have to stick to Northrend until level 78-80.
From what has been said on most of the forums that deal with the coming expansion, once you hit 60 and purchase the regular flying mount training, you will be able to fly in Eastern Kingdoms and Kalimdor. Note, this does NOT affect Northrend Flight...meaning you will still need to purchase the Cold Weather Flying to fly in Northrend.
In Wrath of the Lich King, the mount levels were changed big time. Level 20 will allow you to get your first mount and at level 40 you can get the epic land mount. Level 60 will allow you to fly in outlands. Level 77 will alow you to fly in northrend once you have purchased the cold weather flying skill (level 68 if you have an 80 and can buy the tome of cold weather flight). Epic Flying is still level 70 and costs 5000 gold.
take a boat from stormwind
in northrend
To learn the flying skill, a character must be level 60 and pay between 200 and 250 gold t learn the Expert flying skill. This will allow him to fly in Outland only. To fly in the rest of Azeroth, you will need to also purchase the Flight Masters License. The flight master license will let you fly every where in Azeroth (excluding Draenei, Blood Elf areas and Northrend).
No only wrath to go to northrend but burning crusade to go to outlands among other restricitions
Outland is great! It is a place to level for 58-68. At 68, I would suggest going to Northrend (if you can) and at least doing the initial armor quests and the armor is better than what you would get doing 68-70 in Outlands. After that, you can either go back to Outlands, or stay in Northrend. On a PVP server it may be better if you play on peak times to go back to Outlands as those zones are fairly empty and no large risk of getting ganked. In Northrend there are many daily quests that take 80's to the starting zones, so it is a little more dangerous.
Depending on what class you are leveling, the best way to level is to just quest and do random dungeons. Once you reach Outlands (level 58) leveling will go much quicker, especially when you grab flying at level 60. At level 68 head to Northrend, you will level to 70 in a matter of a few hours.