Hey Jays1fan, sorry that the v2 that I was selling didn't work out. On the plus side, my friend is just about smoke free.
I really liked the V2 product. Really great for what they are intended for, which is to get people off of analogs and to have a relatively problem free experience. That, for me, was only good for about a month. Reading through the forums and researching (looks like that's what your'e doing also and are at the point where you're asking the right questions and I hope my response isn't TOO late but let me try to help you with what I've learned.
1. The v2 passthrough puts out 5.1 volts. It's solid, bulletproof, didn't damage my usb port on my computer, yada yada yada...the problem is that it is 5.1 volts. In order to have a favorable experience at 5.1 volts, your atty needs to be at about the 3.0-3.5 ohm range (or even higher) otherwise, the liquid will burn. What I've found is that I like atty's in the 2.4-2.8 ohm range and the passthrough was just too powerful for those atty's.
2. Yes, it is an 808 connector but if you are interested in the 510 threaded atty's, you can always get an adapter for it, an 808-510 adapter. Many places sell these and it works just fine on the passthrough.
3. Honestly, I am assuming though, I think you are at a point, especially if your hardware is V2cigs, your batteries run at 4.2 volts. Still a little high, in my opinion to open you up to the world of the many different types of attys out there. My suggestion and this thoroughly worked for me is to get a usb VV passthrough. I picked this one up from gotvapes:
GotVapes Cyclone eGo Vornado 3ml Bottom Coil Cartomizer VV KIT [gv-cyclonevornado-KIT] - $27.95 : GotVapes.com, E-cigarette Supplies - Atomizers Cartomizers Mods Juice and more
and thoroughly LOVE IT! It gives me a range of 3.3, 3.7 and 4.1...and you can taste the difference it makes AND it also is bullet proof. This particular package comes with to of the Vornado tanks (don't do well with 100% VG juices but with a little bit of a modification, it works GREAT). Works well with blended pg/vg mixes.
Hope this helped you out.