Getting started programming plug-ins (4.4)

I have never written a plug-in, though I have programmed in quite a few different languages.

I want to write a plug-in that ...
a) requires/accepts input from the user (some kind of dialog, of course), and then, using that information,
b) creates a score with multiple instruments/staves, and
c) writes notes/rhythms in each staff.

Can someone suggest an existing plug-in (or, if necessary, multiple plug-ins) that perform these tasks? I'd like to use it as a template for the one I want to write. I want to get a plug-in that was written originally for 4.4 or has been migrated already. (I have moved to version 4; I have no particular desire to write plug-ins for old versions.)