I would say most transistors are good for analog, digital is just a subset of how you use the transistor, put it into saturation to make sure it is full on. Darlingtons (coupled transistors) are mostly used for digital switching, although some high end amps use them as well. Again, it's how they are used, in their linear region, or saturated.
2) It is generally called the collector current, the current that flows through the emitter/collector junction. But, yes, when you follow one transistor with a second one, the collector current is fed into the base of the latter. This is also used in amplifiers, to increase gain.