Ok, I thought I'd put this in here since it sort of regards set size. It's more in regards to component sizes (i.e. how many abilities, how many weapons, ect.)
Here's the set list in numbers. If it says nothing, then we (players) don't know for certain what they are. Though some of them, it may seem obvious what it is, you still never know. The list is just to show what we
do know, then speculate.
1-16 Heroes
17
18-31 Druid Abilities (14)
32-37
38-40 Hunter Abilities (2)
41-51
52-59 Mage Abilities (8)
60-72
73 Paladin Abilities (1)
74-79
80-89 Priest Abilities (10)
90-96
97-105 Rogue Abilities (9)
106-109 Shaman Abilities (4)
110-119
120-129 Warlock Abilities (10)
130-134
135-141 Warrior Abilities (7)
142-168
169 Abilities (1)
170-174
175-221 Alliance Allies (47)
222-231
232-275 Horde Allies (44)
276-277
278-279 Neutral Allies (2)
280-282
283-303 Armor (21)
304-308
309 Item (1)
310
311-336 Weapons (26)
337-340
341-361 Quests (21)
At first, I figured it come to 15 Abilities for each class, but either I screwed up the math, or something, but it didn't come out even. I'm thinking probably 50 Allies for each Faction, maybe 20-25 for Neutral.
Feel free to speculate, and correct any of my math if it is wrong =)
p.s. The (#) show the minimum based on which have been revealed. Let me know if I missed something.
p.p.s It's interesting to note, Pets are, for listing purposes, included with their respective class' abilities (i.e. Fury is listed under Hunter Abilities, not Neutral Allies).
Kingdom of Karr, Part 1-2 (weekly story + Stormwind Test Video)