upload images- file names

I’m helping move a blog over to wordpress. Their current style is, each post has a preview that includes a thumbnail and the first x lines of the post. The post then has all the content below the full size image. Right now, I can achieve this format by just generating a thumbnail manually, uploading it and then referencing that thumbnail in the post’s excerpt field (via the img tag).

Ideally, I’d like some plugin that can manage all of this automatically (generate an excerpt that includes a generated thumbnail), so if any one is aware of such a plugin, I’d appreciate some direction.

However, if a plugin doesn’t exist, I don’t mind manually generating thumbnails and the image tags, BUT WordPress makes it more difficult with its upload management API. Specifically, it puts everything in a shared upload directory and renames the files. Thus, when I want to reference the thumbnail within the excerpt filed, I need to figure out what WordPress upload the image as. I would like –if a plugin isn’t available for the whole need–to just reconfigure WordPress so it uploads the files of some post into the same ‘directory’ of that post, with the same name. Is that possible? Does my questions make sense? Any input would be greatly appreciated. Take care.