You are correct with Polling - it is Indigo sending a status request to devices. It is NOT Indigo sending a command (on/off etc).
Most Zwave devices send their status to Indigo whenever they are changed locally at the device (light switch, plug-in socket, sensor). If it is say a plug-in socket that has power-metering in, the device might only send 'I've been turned on' - so with 'only when activity detected' Indigo would then poll for the power level value.
On the other hand, I have some Greenwave power strips that never send their status when operated locally. Therefore Indigo never knows whether they are on or off. Therefore it needs to poll every x minutes to find the status.
It depends on the plug-in devices you have whether turning off Polling will stop Indigo knowing the state of the device if you change state locally on the device. It won't stop Indigo controlling it though.
Wake up is not what you say. 'Awake' means the device is listening for instructions from Indigo. These might be on/ off instructions, they might be status-requests (ie Polling), they might be 'change parameter' instructions, or they might be define&sync instructions. All mains-powered Zwave devices are permanently awake. You can send them instructions any time and they will immediately do what you've said. Once a mains powered device has been 'included' into a Zwave controller (eg the Zstick) you should never need to press it's little button again - all changes will happen live.
Battery devices on the other hand would soon die if they had to listen for Indigo instructions 24/7. They live in a low-power state, enough to perform their purpose (eg PIR sensor), but not enough to communicate with the Zwave network. When they need to submit a change (PIR activated) they briefly connect to the Zwave network for long enough to send the necessary data to Indigo.
These battery devices all have a setting in them (sometimes fixed, sometimes settable by a parameter) that determines their wake interval. 1 hour is the usual default. Every hour, they will wake up, connect to Zwave, and wait a short time to see if any instructions are waiting for it. If there's any waiting, it does whatever they are, then sleeps again for another hour. You will therefore never (?) find battery-powered switches that receive on/off commands from Indigo, because they'd only ever action those commands every hour or whatever their wake period is. Not much use if your light only turns on or off every hour.

If you want to make changes to a battery device, you can make them any time, and they will usually pick them up when they next wake up. If you want to force the change immediately, you can go to the device and press the little button inside (or whatever it says in the manual) to wake it up. If it's a complex device and you're trying to re-sync it, you might need to keep pressing the button every second or two to keep the device awake long enough to send/receive all the necessary data for the sync process, otherwise it will sleep again.
Hope that clears things up?