@elextr for me personally, 2) would be more useful than the home directory (the current default location) when creating new files in a project. Usually I open some files first, to read where and how the new file would work. But it would also be fine when I start a new project: my projects are in a directory structure based on meaning (something like `/home/danuker/projects/learning/clojure/brave-and-true/`). So, for a new learning Clojure project, I could just go one up the directory stack instead of having to go to `/projects/learning/clojure/` again and again.
I guess number 3) is a ticket for the plugin, since the plugin has to use Geany's interface, not the other way round, as you say :)
Seems like the plugin [is in the repository though](https://github.com/geany/geany/blob/e2d2a569f27e7bc02b5776ef2d68771b0ff902fd...).