The Twists definitely have quite a following here on the forums. If you want the simplest and one of the cheapest entries into the world of variable voltage, they are certainly a viable option. Without doing a whole lot of extra searching, here is one more:
FreE-Volt Variable Voltage Tube Mod
That would give you the option of running all the way up to 6v in .1v increments, displayed on an lcd screen. It also has replaceable batteries so you don't need to chuck the thing when the battery runs out, which would be the case for the ego.
As for the second part of your question: There are many different kinds of tanks out there. With a lower-amperage or amp-limited device such as the ego or the Lavatube v.1 (the link above), I would recommend a tank that uses single-coil cartomizers, or single-coil replaceable heads. Beware that though the Vivi Nova tanks are very popular and have a large following, I've had problems getting them to work correctly, as have many people here on the forums- but if you have the time and patience to fiddle with them, they can be a great choice. Sometimes, they even appear to work right out-of-the-box. As for single coil carto-tanks, I know they are around. There is a plastic one for sale at puresmoker, and if you want something high-end, Phiniac is the end-all brand for glass tank systems.
The DCT tanks (dual coil tanks) are also a cheap and popular choice. But if you are looking for more vapor and TH, a low-amp device will simply not give you enough power to fully utilize the dual coils. As the tanks themselves are fairly cheap and easy to find these days, you can always use an XL single coil carto in place of the dual coil that it will come with. I personally would not use dual-coil cartos on a device under 3 Amps (some will say you need 3.5-4 amps). And remember that the more power you use, the shorter your battery life will be.
Extra supplies to consider would be extra heads for a tank that has replaceable heads like the Vivi, extra cartomizers for a tank that requires cartos, a carto punch to punch holes in your cartomizers for use in a cart tank (they do come pre-punched as well, sometimes), a syringe top for your liquid bottles for filling, and lots and lots of paper towels. Tanks can be messy when you first are figuring them out.
All in all, there are many, many choices out there to suit your needs, and what I've described here is only a basic list of some of the more common types. You may want to research clearomizers as well for the ultimate in simplicity (they are not my specialty), and higher-power devices to power DCT's. In fact, just research everything before you buy it- it will save you a lot of hassles.
Happy Vaping! Best of Luck
