Yes, I agree for the most part sound quality is always better with stock pads. You can see zeos use different pads here: https://youtu.be/R869ABpfdaM?t=1092 and he doesn't think it makes as much difference as other headphones. It's interesting how he puts the pads on ear first haha. I think I will order the Brainwavz sheepskin and try it at least.
Yes, I will get a step down transformer thank you. Is 200 watts enough?
Not always. It really depends on the headphone.
I've never used a transformer (I used a modified power supply instead) so I'll leave that question for others to answer.