To get heirloom armour you must have a level 80 character and do heroic dungeons or raids. From these you obtain either Emblem Of Triumph or Emblem Of Frost. It is using these that you can purchase heirloom armour; Chest, Shoulders, and One-Handed Weapons are 40 Emblems each, Trinkets are 50 Emblems, and Two-Handed weapons are 65 Emblems. However, you can also obtain Stone Keeper's Shards from dungeons and raids when your faction is in control of Wintergrasp; you can use these shards to purchase shoulder armour and weapons from the Wintergrasp vendor.
Currently there are three sources for heirloom items, plus a single unique one:
Emblems of Heroism
There is a vendor in Dalaran, to the right of the other vendors, who sells heirlooms for Emblems of Heroism. These are chest and shoulder pieces, weapons and trinkets.
Wintergrasp
The antiquities vendor in Wintergrasp Fortress can trade your Stone Keeper's Shards for heirloom items - these are more PvP oriented, and all have Resilience. Again there are shoulders, weapons and a scaling PvP trinket. The number of chest items seems limited. This is the only place to get spellpower plate shoulders or an heirloom gun.
Tournament Grounds
At the Argent Tournament you can also buy heirloom items for the marks you gain from doing the daily quests. This is considered to be somewhat less beneficial, since there are many other rewards these tokens can be used for.
Fishing Tournament
A special heirloom item that deserves its own category (its unique) is a ring which grants a 5% boost to Experience gained. The only way to get it is by winning the Kal'uak fishing derby held every wednesday. Look for the Kal'uak in Dalaran near the fishing daily questgiver to know when it is near.
Heirlooms are armor and weapons that are purchased from vendors in Dalaran and Wintersgrap. They are purchasable by badges (Dalaran) and Stonekeeper's Shards (Wintergrasp). They are not made or dropped.
World of Warcraft: Yes, Death Knights can wear the Bind to Account heirloom armor if they have an 80 on their account with the means to get it.
orc gear
wrath
might
Priests due to the fact that they have cloth armor.
There is. Some vendors sell armor that doesn't have any stats on it which is basically a waste of money unless you want to buy it to RP(roll-play) and then there are some people that sell tier armor that you need to get tokens or whatever it is in the new expansion in order to get.
I will treasure the heirloom. An heirloom is a familial treasure.
The heirloom gear is considered ilevel 1 no matter what level you use it at. This means that the only enchantments that you can put on it are Pre-BC enchantments (the ones that don't have a level restriction).
Find an armor vendor and press the repair button in the transaction window.
Don't worry about it. Just do dungeons and level up.
Warriors can upgrade from mail to plate armor at level 40.
The correct spelling is 'heirloom'.