Prelude: a stopwatch, a full length mirror and the Animator's Survival Kit are all extremely valuable tools.

1. You probably will want Skip Frames On which (in theory) give you a real time playback based on the complexity of your scene. Your animatics pass will be to work out broad strokes of timing - translating a character from point A to point B for example. Once you're satisfied with that, you can introduce final details such as hand movements and "secondary movements" such as fat jiggling. Work broad, then refine.

2. Overall I have no problem with your workflow. See point one.

3. Theoretically there is a possibility that some things will get lost in translation fro one program to the next. To me, the only reason this may be a problem is: sounds like you're planning to render out of Firefly? If so then you will have to translate your shaders and if you need to redo your animation curves too, it seems like you're doing 4 times the work necessary. I mean, your best choice would be to try the conversion between programs on a test animation, maybe one that's a little demanding, to discover any potential pitfalls. Personally I would try to keep all the animation within one program or the other.  

4. the graph editor is for timing AND intensity of movements. Obviously the distance between keys determine the speed of your hand movement. The vertical will represent the magnitude of your movements and the spline types of the keys determines how keyframes transition from one to the next.

Epilog: As they say in my line of work, stop nuking it (and just do it). It's not difficult at all once you invest the initial time understanding how everything works. My first two step walk cycle took three hours. Now I can produce a better two step walk cycle in 10 minutes.