I now have Cubase running not too badly, and all the MIDI is going in and out. I have finally gotten the cables plugged in so the signal travels all the way through. The biggest obstacle here was my master keyboard (Roland A90EX), because I did not realize that in order to use the MIDI THRU port, you have to have the signal coming in MIDI IN 2, not port #1, as most would assume (including me). I fought with this for a long time, but have reached the point where it (sort of) works all right now.
Although I am running Windows 7 64-bit, I have Cubase 5 32-bit loaded now, as I thought it would work better with my older projects. Once I've done some experimenting, I may gingerly proceed forward with going 64-bit instead. The only problem there would be having to reload all my NI Komplete stuff, as it's just installed in the 32-bit version for now. It takes hours to put these libraries and apps in, but if it's worth it to go to 64-bit versions, then I'll put in the time and do it if I can be eventually rewarded with better performance. I was starting to think that my M-Audio Fast Track Ultra USB interface was the problem, and I was going to walk it back to the place where I bought it and exchange it for another brand of interface (and probably FireWire instead of USB). Now I don't have to do that, as I think it will work well enough to keep.
The problems I'm still having are these: I still get the odd MIDI hanging note that screams on by itself until I locate it on the keyboard, tap it, and then it stops. The other problem is the fact that when I have four or five MIDI tracks playing, there seems to be a slowdown happening, and the timing is going south a bit. It's like there's an overload in there someplace. Also, the green MIDI OUT bar on the Cubase transport bar pulses in a periodic rhythm when nothing's playing, as if there's a signal there someplace, but there is no sound being produced at that time.
Aside from this, I think I'm finally getting somewhere. I will now need to know how to change my username on this forum to something a bit more positive, and I'm by no means done posting. I will definitely be mentioning how things are going from time to time, but it's still great to be able to share and get support and encouragement.