Kmuland:
The wikipedia article on time signatures has some good general info on time signatures...
http://en.wikipedia.org/wiki/Time_signatureIf I understand correctly, trackers have an internal clock that cuts time into units called ticks, and then process one line of your tune every n ticks of the clock. So if you track a tune at 8 ticks per line and then play it back at 4 ticks per line, it will play twice as fast. 2 ticks per line will play twice again as fast, etc. This setting affects the way some effects work.
As for row highlighting, I'll do better than a list- you can have a formula that tells you how long to make your patterns and what to highlight. Let's say you want to use the n/m time signature and track with q measures per pattern, and you want to divide each beat into p parts. Then you need to make your patterns n*p*q rows long, with your major highlight every n*p rows and minor highlight every p rows. (other people feel free to check this...)
Basically western pop music has been bound to the 4/4 time signature since, well, basically forever. The purpose of this compo is to get us thinking outside that restriction.
I'll try to get something together; this will be my first compo (if I finish something, that is...)
EDIT- my math was off