1,2: We don't have an editor. It's more "Evernote for sheet music" than "Dropbox for sheet music" for two reasons:
a. score organization/management with cloud infrastructure.
b. image processing (importing paper scores via the phone's camera) and OCR features that we're working on (not released yet).
Which means it has intelligent features rather than just doing syncing of scores.
3: Those should probably become "Upload" and "Library" respectively.
4: That was a tough call. We wanted to communicate in the landing page that iOS devices are supported (through the web app). If we didn't put the icon, people would think that there isn't iOS support.
5: Got it.
6: Sorry about that, we fixed it.
7: We will probably add Esc as a way to exit the gallery.
8: I can see what you mean.
9: Can you elaborate? You can also try the zoom functionality in the single page view, it's different there. You can turn off split page view in the preferences page (click on your username -> Preferences).
10: You can't do it from the web app at the moment. The Android app is needed to do this (for now). Any edits done from the Android app will get synced.
11: Can you mention some of the things you dislike about the upload form?