Mat quality does NOT matter (bronze/ silver/ gold). Just get the cheapest. Exception to this seems to be 元素调和 for 无瑕的凝结龙晶, which apparently requires gold quality. Fortunately, gold quality 元素调和 IS the cheapest on the AH.
To teach the recipe to the crafter, you just target them and right click 远古记忆 in your bags. Using it makes it go on a 30 minute CD.
Recipe seems to disappear from the crafter after a while. Not sure of exact duration--it's under 24 hours. Maybe 12 hours? Crafter does get and keep a knowledge point for first craft of this, so that's a nice bonus for them.
If a crafter has 2 of the crafts listed (BS, eng, jc), it will randomly teach one and then refuse to teach the other when you recast it on them. This is based on what happened with friend's eng jc. Had to get him to use an alt with jc. Could be specific to jc eng?

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Also, here is a cool weak aura (not mine, all credits to the author) for tracking all the mats you're collecting for 纳兹乌罗，无拘传承:

小知识

屏幕截图

视频

无瑕的凝结龙晶

物品等级：500
拾取后绑定

需要等级 70
制作材料
"乳白色的宝石，以统一的步调旋转着，表现出了完美的和谐。"

指南