BEXIL160 good questions.
1. I have not flown the DET-BPK-TNT route before, but looking at a high altitude chart, BPK-TNT does not have a connecting airway, so the portion must be DCT routing. Maybe that is the confusion, i.e. the crew looks at their chart trying to figure out how they "connect the dots." This is just speculation, and the only reason I can provide.
2. In our case, we do not have FMS, etc., so sometimes, when asked for our requested final altitude, we do a quick computation to see if the actual temperatures aloft will allow us to go higher, i.e. not the "forecast" temperatures. So, there might be a slight delay in answering your question. This delay (90 seconds plus/minus) may give the wrong signals. Yes, we know what our requested altitude on our FP is, but maybe we would like something a little higher.
I hope this sheds some light, IMHO. Maybe others have a different spin on your questions.
Cheers,
