I too recently bought an MD-8. A very nice piece of equipment. For the bass, it might be that I'm not very sophisticated, but I just plug the bass right into one of the track inputs and play, and it seems to come out okay on the mix for me.
For Green Hornet - As far as bouncing tracks, there is a track copy function in the edit menu, where it picks up one track and lays it down in the track of your choosing. Or, you can use the group record function and redirect the track that is playing to the selected group track. (the overdub with playing function. But the whole grouping thing is not the most clear thing, I'd go with the track copy)
Speaking of neat functions, I just the other day figured out that you can select a segment of a track with the record IN/OUTs (like a vocal line) and lay down it in an empty track a couple frames behind for nice thickening of the sound (1 frame - thicker sound, 2-3 frames - slight delay, 6 frames is too muddy) BUT, I'm trying now to make a rhythm pattern by chopping up a single chord strum into different segments and arranging them. Fun stuff. I'm so glad I don't have to screw with tapes anymore.
FW