I am really confused as to what Samba actually does and how it works. Here's what I'm hoping it does:

I set up a Samba server on my LAN, and everyone will be able to see each other's shared files and swap them.

But some of the documentation makes it sound like it will just allow Mac/Linux computers to see Windows computers.

Other bits of the documentation make it sound more like a local server, where a Linux machine would install Samba and they would see everyone and be visible to everyone, but that won't change if anybody else can see each other.

While still other things I've read make it seem more like a file-server, where everyone sees each other but file transfers are not peer-to-peer but instead need a host disk for files to act as go between.

So, assuming I'm even in the right ballpark of what Samba does in terms of my goal of total cross-visibility on the network, I am left with needing to know what I'd need to set up the server and whether it can be done and is worth it...

DD-WRT's article on Samba is a bit ambiguous. One second it sounds as if I can run the server on micro as long as it's set up on a usb drive, but then it also sounds like micro can't run it at all, etc.

If I can run it from a usb-connected drive, I still need to know if the files are actually stored on that drive. The dd-wrt article mentions:

You can run a Samba server on your main computer and run a client on your router (thus gaining writable storage for the router) or you can use Samba to share a drive connected (typically by USB) to the router among all the computers connected to your network.

That one part "to share a drive...among all the computers" makes it sound like the only benefit I get from Samba is a share drive that any OS on the network can see, but they still won't see each other. But I'm very hopeful I'm misreading this.

If the computers can see each other but still need the disk, how much space is generally a good idea? I'm basing this on the idea that the drive is a temporary store point. Obviously I'd have to get a drive big enough to store everything people wanted to share if the drive is a full-on file server.

If I do have this all wrong, is there any software that achieves what I have in mind? Something that connects to the main router to bridge all clients?