Be careful, I do now know about caffeine but nicotine is a poison, and very harmful poison in certain dosages.
About PV vs e-cig naming, I use to answer "electronic cigarette" to sporadic curious who ask me "what is it?" but I personally call PV to my devices because I do not find enough similarities with burning cigarettes. What I call "e-cig" is to those super-mini devices, which are much more similar to burning cigarettes than my Tornado PV or many other mods I've seen.
From another point of view I think we need to differentiate PVs from simple e-cigs. On the one hand, I assume that e-cigs are for those who want quit smoking gradually while reducing the hurt to their body, so need a "thing" as similar as possible to their current smoking habit. On the other hand, I assume that PVs are another different device for those who want something different or want continue with serious "vaping" and occasionally will finish with 0 nic juices.
Edit: Aroma Therapy Device (AT or ATD) is another cool name