Thanks for contacting us. #1 Do the coil caps fit universally on any of the coils No. You have to choose the cap for your exact device, for example the replacement cap for Yocan Evolve, this part is NOT compatible with Yocan Regen item.
#2 Can all of the pens use the hanging ring, if not which can Yocan Regen, or Yocan Evolve Plus XL
#3 Where do I get caps for the Evolve D tobacco coils, description said caps not included This part is unavailable on our site at this time. please go to the local head shop to find this part.
#4 Which pens or vaporizers can use the tobacco coils Yocan Falcon, or Yocan Evolve-D version, and Yocan Evolve-d Plus Version
#5 Which pens or vaporizers can use the Ceramic Donut Coils?Please choose Yocan Evolve Plus 2 in 1 kit. And please go to the local head shop to get this one iem.