Share files with users. Is Monstra for me?

Hi!

Stumbled upon this which looks really interesting.

I have created an application for my (small) business. The application handles (among other information) invoices for my customers. My idea is to have a web page where my customers can login and download their invoices (pdf-files), edit personal information and (perhaps) do bookings. The information (except the pdf's) is stored in a psql database from which I'm planning to export relevant information to Monstra and then import updated records back to the database. I do not want direct access to the database for security reasons (medical records).

Is Monstra for me? Can I achieve this with Monstra?
Can I from my application upload pdf's to certain users?
Can I from my application create user accounts?

I'm hoping to find a tool for this so I can spend my time developing my main application instead of creating a web service...

Thanks in advance for your input!

hakahl