It's definitely 65 to finish the 1.5, and 2.0 is not useable till 70, even if it can be completed at 68 now (with Anguish opened up at 68). But from memory, it seems Korbuk won't deal with you on the 2.0 until 70. I'm not sure about the pre-quest, but would assume it's 65 to do it, but with all of these, you can pre-complete / pre-loot alot of it before 65. Ground spawns, can be gotten at any level you can in the zones they're in. Work on getting the required language to 100, work on getting brewing and optionally jewelry crafting skils up near or past 100. Kill some of the non-epic triggered mobs for the any of the 3 quests for their drops.
Best thing to do with any epic, is find a checklist (
The Steel Warrior is probably the best place to search, and the best source of War and melee-related information), and see what can be done out of order.
Links to get you started:
War Epic 1.5 Pre-Quest War Epic 1.5 War Epic 2.0 Yther Ore.