I don't know whether these are exact equivalents of how things are done in I6, but this is how they are typically done in I7:
Switching on and off:
See §3.14. Devices and descriptions in the manual.
A "device" is another of the standard kinds of thing, and should be
used for anything which can be switched on or off: a light switch,
say, or a slide projector. Devices are generally machines, clockwork
or electrical. A device is always either "switched on" or "switched
off", but is switched off unless we specify otherwise.
From the example "Down Below":
Terrifying Basement is a room. The light switch is a switched on device in the Terrifying Basement. It is fixed in place.
Carry out switching off the light switch: now the Terrifying Basement is dark.
Carry out switching on the light switch: now the Terrifying Basement is lighted.
Triggering an event to occur after x turns:
The answers to these questions may help:
http://ifanswers.com/282/how-do-i-print-a-message-on-the-xth-turn-in-inform-7
http://ifanswers.com/340/how-to-trigger-an-event-to-occur-x-turns-after-another-event
I don't know how interrupting a timer is done--hopefully someone else can answer that.
Making things happen turn by turn:
See §9.5. Every turn in the manual.
From that section:
Every turn when the location is the Orchard, say "The summer breeze shakes the apple-blossom."