I learned a lot from Carl Licroy (Prophet 08 panel). Without his panels mine would probably look much different e.g. a lot simpler without librarians etc. If I remember well Goodweather explained me the timers which are a very nice way to workaround Ctrlr bugs and ad features that wouldn’t be possible otherwise.
I don’t know where to find the classes. You found out most things yourself:
timer:setCallback(3,PlaySeqCallback) <- This defines a timer with the ID 3, and the timer-method is called "PlaySeqCallback". Look in this method how to set it up. At the end you must somehow stop the timer otherwise it will run forever. timer:startTimer(3,300) <- This starts the timer with the ID 3 and repeats all 300 msec. Yes you can run several timers at the same time, but keep in mind that there will always be just one of them running at a time. When one timer is running, all others will wait (and delay) until the running one stops. You can see that on the Matrix-panel: obviously moving faders has priority, so when you move a fader the pseudo-sequencer will "hiccup".