Those are very good questions, Jason. Let me see if I can answer them a little better.
1. FTP is a relatively uncommon protocol for most users. Our church administrators don't use that protocol at all except for one who uploads a bunch of pictures as a batch. It does a great job for that and I'm not sure if there's a good TYPO3 extension to replace that.
2. Just about everything you've listed can be done using the TYPO3/WEC tools. Most extensions that let you upload a file either let you do it through the back-end or let you do it through some front-end configuration. For example, we put our sermons online and the person who does this is able to browse for the local MP3 file and upload it as part of the process of creating a sermon record. Similarly, if someone does a blog post, they can upload the file through the TYPO3 backend or through the tool they are using. I'd probably recommend doing this method for security over multiple FTP accounts.
Besides, using the security model you've designed, I'd probably be locking down those reports to either pages linked to Front-End user groups or some similar method. The uploads would be restricted in the back-end using their logins and with the logins tied in to whatever folder/folders they would need to access.
It's kind of hard to explain without actually going through it. I think you'll find that you can go through the TYPO3 backend to do just about anything except mass file manipulation. I'll have to admit that I'm not even completely sure about that. I've come across a couple of extensions that are supposed to enable that for certain functions.
Let me give you an idea of what you may want to consider for these sensitive areas (others may have different/better ideas).
1. Create a Front-end user group for your Finance Committee
2. Create a page for your Finance Committee, make it restricted to Finance Committee
3. Add a login or two to your Finance Committee group
4. Log in to the front end as a member of that group and then as someone who is not a member of that group. You should see that the page is either visible or not visible based on those permissions.
You can make this page contain certain notes specific to the Finance Committee, perhaps add a page item to link to a folder containing just Finance Committee reports, etc.
Does this help you picture things a little better?