Questions about crafting a "+2 Sorc Skills" caster amu/ring

I was watching Llama's video (https://www.youtube.com/watch?v=H3UOdIO3Yb0&t=4418s) and he mentioned how to create a caster amu/ring with "+2 Sorc Skills". In the following I will first repeat what (I think) he said, and then my questions.

He said:

  1. To have the "+2 Sorc Skills" (or any other class), the amu/ring that is used in crafting has to be ilvl 88+.
  2. One way to get such amu/ring is from gamling. Clvl has to be 93+. This is because the result ilvl of the gambled item ranges from clvl -5/+4.
  3. (1:16:41 in video) clvl 93 => input amu/ring ilvl 88 => crafted amu/ring ilvl 90

Questions:

  1. Is "Arch-Angel's" the name of the affix of this "+2 Sorc Skills" in the "MagicPrefix.txt"? If so, it does require ilvl 90.
  2. Does the crafting itself adds 2 ilvl to the amu/ring (bump it from 88 to 90, in order to receive the said affix)? If so, reference to wiki, etc, will be nice.
  3. With the correct ilvl, does the crafting always grant this affix, or is it by chance (about how much chance)?
  4. Why require clvl 93 in the gambling? I think Llama probably meant "if you want to guarantee a ilvl 88", right? Because the lowest possible clvl is 84 (with +4 the ilvl will be 88).