Congrats on getting the EVOD Twist! Having variable power will allow you to control the temperature of your vape. Start at the lowest setting and dial up a little at a time and see how it vapes. If you dial too high and the flavor fades or starts to taste a bit burnt dial back the power a little until you have the optimum setting for flavor and vapor production.
The ideal voltage power setting will be different if the oHms of the juice delivery devices are different. Also, some flavors taste best at lower power while others need higher temperatures to shine.
The VAMO is generally a reliable device other than the threads on the ones Fasttech sells tend to be on the delicate side. You can make the threads last longer by using these adapters,
510 to 510 adapter and
510 to eGo adapter.
The menu system on the
ZMAX V3 Telescopic Variable Volt/Watt Mod isn't nearly as friendly as the VAMO but you might want to consider it as it doesn't seem to have the issue with the threads that the Fasttech VAMOs do.
Fasttech sells Nitecore battery chargers. Those will work just fine to safely charge batteries for the VAMO or ZMAX.
I don't know what to tell you about batteries. DHL recently has refused to ship e-cig batteries on their planes which has made shipment of batteries from China very difficult. There is also a huge problem of counterfeit batteries from China. You need 18650 IMR or hybrid batteries like Panasonic makes. Efest and AW make 18350 IMR batteries which are shorter but their charge doesn't last as long. Using 10 amp batteries is more than enough power for the VAMO or ZMAX.
Baditude has some blogged some excellent e-cig battery info that is more than worth a read.
Battery Basics for Mods: IMR or Protected ICR?
Deeper Understanding of Mod Batteries - Part I
Deeper Understanding of Mod Batteries - Part II
Orbtronic is an extremely reliable U.S. battery vendor that only sells high quality batteries. They do
international shipping but you must contact them first. Orbtronic knows their stuff so you will be fine with whatever batteries they recommend for the device you decide to order. These are batteries that can be used in flashlights so you should be OK with customs.