LM suggests to spray it into the intake pipe only. I would advise not getting too close to the throttle body. I only push it in under the pipe where it slips over the MAF, maybe an inch or so.

As you've said, I wouldn't pump the full can in with the engine off. While it's running at around 3,000RPM. It will be more evenly distributed to each cylinder, and the crud will be burnt off in the combustion process anyway.

As for the DSG reset, just do a basic reset. It's just key on (engine not running), with the accelerator to the floor for at least 10 seconds.