A: All of these tools are standard sizes. 1/4" is the small ratchets so it should work.
A: As Long as it is 1/4" drive it will.
A: It's 1/4" drive, so it fits standard 1/4" drive sockets, extensions, and ratchets.
A: Yes it will work on any 1/4 inch drive socket, extension etc..
A: Yes....if your socket accepts the1/4 inch drive. All 1/4 inch sockets should fit on this drive.
A: This 1/4" drive universal joint will fit a 1/4" drive 10mm flex socket
A: They will be close but in the long run you will not be happy. Just that little bit of play will wear out both much faster
A: If it is a 1/4" fitting it should attach just fine but why would you need a universal joint and a flex socket? I'm not sure that you would actually be able to get any torque using the two together but I don't know your application.
A: Yes it is as long as the socket is a quarter inch Drive