Should I use the 3.7v to prime? I did read the vaporpedia page. Also should I hold the cart straight up when filling, or tilt the cart slightly? And should I use a bid lighter or my small torch to fill the cart?
You could, but I always prime at the voltage the cart wants. I hold the cart straight up, but am not sure if that makes a difference. If you use a torch, be very careful not to overheat, or it can cause that taste and/or blow out the seals. The instructions show the cart being held in the hand, so as you heat the top part of the cart, you'll know if the bottom is getting hot to back off with the heat.
It's not that difficult once you get the hang of it, but caution is advised at this step because it's no fun to burn out a cartridge and have to try to get the oil back out. The whole routine, and my concerns about overdoing it, were a major reason why I went with the SR-71, which is pretty bulletproof.
The thing I learned most about the Persei is it's not difficult to overdo things, either by over-filling, mashing on the button if there's a clog, etc. If you took the time to read the vaporpedia entry, you've got some good info to help guide you, as well as many knowledgeable members here. Good luck!
Edit: watch out for ataxian, he's a rebel!
OK, atax, I'd like to know how you fire both those tops at once. Do you have an assistant?