To change the actual connector itself, you need a very small pic. If you look inside the connector (from the plug side) there is a metal tab that locks the pin in the connector, push the tab down while you LIGHTLY pull on the wire. It should come out with a little bit of work.
As far as I know, none of the connectors are available, except the ones for the ignition coils. We are pretty much screwed, electrically, as these cars gets older and the plastic wears out. I just pulled the wire out of one of my knock sensors, and now I get to try and open up, recrimp, and solder the terminal back onto the wire. I HOPE I can do it.
Oh yeah I know you can get the terminals, only if you want to buy 10000 of them.