I think you're creating work for yourself, honestly. I can't tell from the details in your description - but if shell scripts have been working, why structure it where structure was apparently not needed?
You're stating that modularity and repackaging into an external library is something that you'll need to do - I would counter "why?" (this is what I mean by extra work).
If you create a simple set of methods in a single file - that's a single file! It, by definition, will be easier to work with then multiple projects etc.
That said - it's hard to know what we're talking about unless there are some more details. If it's "send a nightly report and email these people" - yeah that's something that doesn't need a class library and a ton of modularity. Run a method, you're done.
