Ask HN: How should I set up an online script review service?

Hey HN, I'm hoping someone out there will be willing to guide me in the right direction.

I'm gearing up to launch a new screenwriting-related website soon. I'll be publishing many articles, but I will also be setting up a script review service, where I ask readers to upload their own scripts, attach their e-mail and pay with paypal. I'll then read and review their scripts, e-mailing their review back to them upon completion.

So my question to you is this: What's the best way to accomplish this? (This being: fill out a user form, upload a file, send all the information to my e-mail, and have them pay). Are there any services out there that could handle the backend?

I'm brand new to this kind of commerce stuff, so I'd be very grateful for any advice you could give. Thanks much.