Gilbert is so lucky to have you Lulu! Timber has a fascination with the tray on his cage as well. I'm assuming that because the grate prevents him from getting to it when he is in the cage, he feels he must check it out when he is out!
How exciting! And what a pretty boy Darwin is. Timber, my TAG, clicks when he wants attention, wants to communicate etc. I think of that as his "here I am" sound. I leave the TV on animal planet for him when I am gone during the day. Not sure he appreciates it, but there it is
Haaa to the "dunking." Timber is a dunker. Sometimes he dips and eats, sometimes it seems he just throws it in there to see what happens. Normal behavior from what I've seen. Chico may actually eat some of what he has dunked, then again he may not! Sorry this isn't really an answer, but that's all I know!