Coil operational test & coil fit over plugs

I noticed a mention of this test on the post about spark plug replacement here

DIY for an M54 spark plug replacement on a 2002 BMW 525i E39 - http://www.bimmerfest.com/forums/showpost.php?p=5985803&postcount=1

I am curious to as to what is this test exactly testing and how do I use this test to check on the coils after the spark plug replacement I completed couple of weeks ago.

Another related question is that I found the coils not going in all the way to grab the connectors on top of the plugs. This was on all the plugs and certainly not the issue of the rubber boot from socket stuck to the plug. The coil were just sitting/floating on top of the plugs and I was able to push them in as I tightened the 10 mm bolts.

Is this normal that the coils don't grab on the plugs until tightened with the bolts.

The car is running fine except for some tapping noise I heard when the car was warm which I have read can be related to the ECU getting adjusted to the new plugs.

Thanks for the all the contributors that have posted the DIYs. I would however like to say that it is kind of hard to find 540 (V8) specific DIYs at times.