Celestial items

Hi guys,

Newish player here. The celestial smithy- where can I find the less common items from this smithy list? I was thinking of crafting one of the two celestial staffs, but I only know where the staff of 7 are.

Also, regarding the staff of 7- how to combine those?

Thirdly, are those celestial staffs base “staff” so feats work with it? Or are they both magic staff…. Which means nothing works with them? (Like dev crit).

Thanks!