Cross Sell, Easy populate and Products Model

Okay, I had a couple of questions. Might as well start with the simplest one -what is a Products Model for? I've been trying to find some kind of definition for it, but my searches are coming up with vague references, but no real reason for the field. Maybe I'm searching the wrong term or something, I don't know - but if someone could shed some light on it for me, that'd be great.

I ask, because I'm using cross-sell, and I checked out the "cross sell advanced" - it associates things by products model, which is a field I've never really even paid attention to before. So if I'm gonna use it, I guess I need to know what it is :)

Another question: has anyone figured out how to get cross sell to work with easy populate? I've messed with easy populate myself quite a bit - for this site I've actually gotten 3 description fields in there that are working great, but I can't figure out how to get the cross sell to integrate with easy populate (so I can just do it all in one spot). So before I buckle down and start coding, I was just wondering if anyone else has managed to get that to work.

Any help with any of this is appreciated :)