Hi tvkyq,
Here! Please post here! I know exactly how you feel; learning Bokeh was a lot of copy-and-paste-and-hope when I first started using it, and if I had known about the support forum at the time, I would have saved HOURS. If not days.
Please don’t feel awkward about any question, especially when you’ve tried to do something according to the docs and you’re finding it doesn’t work. I say this for a few reasons:
- It highlights areas in the documentation and/or user guide that could use improvement.
- It’s likely that if you’re having trouble, someone else is having or would have similar trouble, and just by posting on this forum we’ve shortened their search when they do.
- In some cases, it could even expose usability issues and use cases that are worth a rethink in the code.
- We want your Bokeh experience to be great, with you making neato interactive data visualizations, --NOT frustration, grinding away at some counterintuitive python quirk.
Plus, all three of your questions sound like great questions of general interest. I’ve investigated a couple Legend ones lately, so I’m personally curious about behavior you’re seeing there. 
Please don’t be shy about pasting in some code. You’ll see a wide range of coding styles and abilities if you look through the Discourse. Everybody is learning all the time.
So please! Post here, and welcome!