I'm thinking about buying it, but I need to make sure it does a few things first.

I am looking to make something like what I have now http://simscollaborative.com/index.php?action=downloads

However, I am looking to add thumbnails to all the posts (so people can see it before they click)
As well as multiple images on the post and then multiple attachments? Is there any way I can try and make sure it works and works with my theme before buying? If it does everything I need I would buy it in a heartbeat.
Also does it work with the portal?

You can add multiple images and files for esch download, a block for portals is provided and sorry but I cannot give you a copy for testing, if your theme was done right it's going to work effortless

Will the images be able to be inserted into a post like this? From the upload screen, where there is the large images, and then a section where all the small thumbnails are? Or will the images need to be uploaded somewhere else?
Can you post up an example of what a download section would look like with 4-5 large images? (I don't need the tabs like in the example, they use a custom system, but I do need something that is just as functional)

http://modthesims.info/d/457428

This is what I'm trying to achieve, at least similarly

Well, images could be added into downloads using BBC (included by default), and there's already a section of thumbnails