(Note: this is cross-posted on Stackoverflow here.)
For the second question, you can directly link to a specific notebook in the path. However, it sounds like preferably you want the interface to not just be the default notebook as well. For that you can use Appmode or Voila. For both of those you’d also need to specify opening the specific notebook, in the form of an app now, by using the URL. For Appmode, this is addressed here.
More along these lines has been discussed here, here, here, and here.