They only mention Trowzer, even though they write it as literally Trouser. The group behaviour from enemies is something they have mentioned before.
The only knew information I got out of it was that Playtonic seem to spawn randomly. So their effects are most likely to be non-permanent I think. (Since it would be unfair if one player gets all those great Playtonics in the first level, and another doesn't) Also Playtonics will provide some RNG for speedruns.
What????? Enemies burst into smoke when killed? I loved the gorey parts that just went everywhere. I really wanted to see 50,000 particles burst out of the character and scatter in places since we're running on more powerful hardware nowadays. Oh well.
Oh, good eyes! I didn't catch that at first glance =) To answer you question : why not both? An idle animation could be Yooka resting on his tail like a stool or using it like a spring and hopping from time to time. Of course, this could be an ingeneous way to animated the "high-jumping" technic!
Well from a offscreen play Yooka-Laylee team had on E3 I was able to (Poorly) make a map of the areas shown in a top view, please be aware that joining this together really takes a lot of work and if someone can and wants to do a better version you are more than welcome. SPOILER ALERT!!
If you think this can spoil your game, even tho it is far from finished, then DO NOT OPEN the spoiler tag.