If the computer has (Mini) DisplayPort, then you can use it. Otherwise you need to get a hefty adapter (150-200$). There is e.g. Dell U2711 that uses the same panel as 27" ACD if you are in market for a new display.
That is according to the Apple website, but I don't see why it couldn't be used on another kind of computer. There may be only basic drivers to support it though.
No, you can't. Those cheap adapters transfer mDP to VGA/DVI/HDMI but not vice versa. Adapters that transfer HDMI/DVI to mDP cost 150-200$, e.g. Kanex XD.
No, you can't. Those cheap adapters transfer mDP to VGA/DVI/HDMI but not vice versa. Adapters that transfer HDMI/DVI to mDP cost 150-200$, e.g. Kanex XD.
ACDs are pretty expensive already, if your PC doesn't support MiniDP, I don't see the point in buying one. Better off just getting a different display.