Hey man, good questions.
- I usually watch, on average, ~5 videos on DTube per day. I usually use Busy.org so I am not looking through the DTube website and am instead consuming any kind of content. I'll watch videos from people I like as well as videos that people resteem because I like blog posts as well so I will read that stuff too.
- It does play a role in my decision to start watching a video, but it will also help me determine whether I will continue watching the video. I probably will not stay engaged in a DTube video over 10 minutes because most people here are amateurs and don't have the knowledge to keep someone engaged for more than a few minutes. Often times, longer videos are a result of people not cutting out fluff and unnecessary detail (like you said). A lot of videos that are long could have been cut from 12 minutes to ~5 minutes.
I'm not familiar with busy.org I'll have to check it out. I agree with number 2 and it's an interesting thing; on youtube you want to make your videos purposely long now-a-days because watch time is how they determine popularity and dtube doesn't care about watch time or views it seems but rather the quality of content.