I have three questions about item crafting:

1) Is there any advantage to using high level items in recipes? For instance, you need a hot edge (of any level) to make a searing edge. Is there any difference between using a level 10 hot edge and using a level 1 hot edge to make a searing edge?

2) Can you variant stack? For instance, can you have one Ash of Agni with 5 unique variants on it?

3) Does crafting higher level items give you better unique variants? For instance, do you get better unique variants for making a Shivermist Buster vs making a Haze bomb? (An example of a "better" unique variant: Medium damage vs undead is better than Low damage vs. undead.)