I think to make it possible you would have to use more powerful tool than WFS, which is limited in the features it has and even more in those it lacks. The situation and forum since last time you asked did not change.
Heaps, but writing a complication is several orders of magnitude harder than designing a clockface. There’s an overview here. Follow links from there. The samples repository is also worth a look.
Yes, that should be possible.
If you add 4 time elements and set each of them to desired different time zones, you can stylize masks over them to pick the style with your desired zone. Check this answer to a different question, which makes more sense for you, than for the original poster in that thread there (the example was there just for 3 variants I think).