Yes, with FBX export it should be useful with Unity. I think I'll check it out. I'm a LightWave guy but increasingly disillusioned and looking to expand my toolbox!
DAZ Studio Pro seems to be for both Mac and Windows. (The site doesn't seem to list sys reqs anywhere, but Wikipedia--which also says it's been free since Feb '12--states Mac and Windows, and I see bits of both Mac and Windows UI elements in the help section.)
I think Daz is always free. It has been, at least, for the last year or so. I use it quite a bit to knock up quick characters but haven't tried it with Unity yet. The models are high poly count, so you can buy Decimator to help you reduce that.I'd highly recommend it for non-3D artists or people pushed for time. But don't be fooled by the free aspect, the expense actually comes in from the asset store. Daz3D on it's own is pretty basic and you'll soon find yourself asking how to do 'this' or 'that' and then finding the answer on the asset store with a nice price tag attached 😉