Yeah thats what I meant by youll need an adapter. A 510 to 510 adapter will give the extension needed to use most tanks. And if your just going to use cartos, then its not really an issue.
The High-Drain batteries are def the way to go for any unregulated PV and I promise youll notice the difference, and their def worth the few extra bucks.
The High-Drains you have now will allow you to vape at 3.7V, but you can also get other batteries for 5V, 6V, or 7.4V.
I buy all my High-Drain batteries from Super T Manufacturing, and I recommend checking them out if you ever want different ones for other voltages, or just want to grab an extra IMR 18650.
Super T sells a wide variety of AW protected batteries and AW IMR High-Drain batteries. If you want high-drains, make sure they say IMR, otherwise they are NOT High-Drain batteries. I also like Super T bc their shipping is only $1.71 if your order is under $36.
The switch is def alittle shoddy, but just be careful with it and you should be fine.