Is it correct that the whole cartomizer has to be tossed once the coils are done?
Yes, cartomizers are not like the coils in clearomizers, you can't rebuild them. They are disposable, so once the coil stops working you throw it in the trash.
I'm curious to try refillable cartomizers though, for tasting juices without having to empty, clean, and fill up a whole tank.
Cartomizers are very difficult if not impossible to clean one flavor out of. You would basically have to remove and replace the batting material since it is designed to retain and hold the liquid.
Also, as it correct that cartomizers are what is used for 'dripping'?
No. Dripping is entirely different. A dripping atomizer has no tank or cartridge to hold the liquid. You drip a few drops of liquid directly on to the atomizer (Coil), there is no storage for liquid at all.
This is an RDA (Rebuildable Dripping Atomizer)
This is also where the term "drip tip"comes from. You remove the tip to drip in more liquid.
The other type of dripping atomizer is rarely seen these days, but it's the prebuilt 510 dripping atomizers. These look like cartomizers, but without the batting material.
One end is open and you just drip in a few drops of liquid straight on to the atomizer head.