1. Hot topic of debate in my LS and many others i know in the crafting circles. Personally I don't give it much thought, have HQ'ed under every lunar phase. Conversely I have also NQ'ed under lunar phases RNG......

2. No, it is all RNG it seems. I had the same crafter make me up a batch of Crab Bows. All the attempts were 320+ quality/110+ durability before touch up... and all went nq. The next day i had someone burn some nq mats and i got a +1.

3. For finished items i would say yes this is true, for parts i haven't found this to be true.

4. If you want +2/3 finished items then yes using some or all HQ parts is the way to go. The exception to this would be on items that you (the crafter) severely outrank. Think a gold smith R50 making Bone Rings etc(rank 1 synth)...