#1: I think the GeanyVC plugin does exactly that.
Yes, I've enabled this, but it seems very primitive and nearly unusable. All actions are under a "VC" file menu, and not accessible in the tree browser, so it's very clunky and difficult to quickly see what's changed. What's there doesn't even seem to work. Selecting a directory in the project tab and then doing VC->Directory->Diff just gives you a status message:
14:43:54: File /home/chris/git/myproject/src/someotherdir: action diff executed via git.
but it doesn't show you the diff. Also, I had selected `/home/chris/git/myproject`, not `/home/chris/git/myproject/src/someotherdir`, so the command isn't even correct.
Regarding #2: AFAIK, you cannot do that in Geany, but you can start Geany twice, and
open a different project in each instance. Other than that, you can open any file regularly with File > Open. Also, I think there is a plugin that adds a full filebrowser to the sidebar, but I haven't used it yet.
I literally have hundreds of projects, of which I'll typically have a few dozen open at any given time, so it's not practical for me to launch dozens of Geany instances. This sucks. I really hate Eclipse, and that's the only real show stopping feature gap.