On the move, so quick answers: you are right with your guess. You can have 64 tracks playing at the same time. You can have tracks assigned to individual midi channels. Or you could have them all point to the same midi channels. Or a mix of both. Many possibilities. You have two Midi DIN ports (so 2x 16 channels) plus USB midi out. That’s a total of 48 midi channels.
Also, you can store CCs and Program Change Messages alongside with note messages. Or keep them on a separate track. Again, many possibilities. To add to this, Pyramid TRACKS can hold PATTERNS. So on one TRACK you can store a lot of different melodies/loops/parts.
The only upper limit you will hit with big projects is the midi events limit. (It used to be 7000 midi events but has improved to around 8500 with the latest update). This is a hardware RAM limitation. Don’t let that stop you, you can still do a whole lot… but it’s a limit, nonetheless.
Ok, that was not so short but I hope all clear now. Peace!