Hey candace,
It sounds like there is some doubt in your mind that DNN is the right tool for solving these issues. I think that you should always explore the nature of the task (i.e. requirements) and evaluate what the best solution is - and as such would like to help you make sure you're going to be happy with the solution you implement. :)
You said that the scheduled task would normally be run by the windows scheduler - why have you decided to use DNN in this case? By very nature, the windows scheduler will be much more reliable than anything that runs from within a web application. If you don't have a good reason to use the scheduler in DNN (and there *are* good reasons - to be clear) - I would recommend using the scheduler built into the operating system.
And I'm not an expert in the fine art of sending mass emails, but it seems like there would be a more elegant way for you to send emails to the people in your CSV file. If you had users that were already registered on your DNN site - that would make more sense to me, but...
Anyhow, these two tasks sound a little bit more like an excuse to mess around with DNN - and there isn't anything wrong with that (especially if you're going to be using DNN on a larger scale in the future) - by all means, get familiar with DNN, you'll probably really enjoy it. However, if you're just trying to solve this problems because you need to - I'd suggest re-thinking introducing the learning curve that comes with a new technology until it is warranted. I, by no means, am trying to scare you away - but just start a dialog to get you thinking about these things - I hope it helps!
Take care,
Ian