1A is about the limit you can push through a mini-B USB cable and connector. To go higher, you need a different connector type. The USB A type connectors can handle more current than the mini-B or micro-B type connectors. Even so, the spec only goes up to 1.5A for those.
Barrel connectors are typically used for high current requirements. You seen them used commonly for Laptop computer power ports. Those can handle currents up to 10 Amps.
That 5A USB adapter from New Egg is actually 5 ports at 1A per port so that wouldn't be able to supply the power you need for an e-cig either. The highest I've seen for a single port is 2 Amps.
You pretty much have to have a battery in an e-cig that has a USB power port. The battery provides the high currents and the USB supply charges the battery.
For something without a battery, you'd want to use a high output supply with the required connector and cable to support the high currents. It's certainly do-able and lots of people have done stuff like that. The first VV mod I made when I first started vaping was like that, used a 5A supply. That was before VV or VW devices were commonly available.
