More trouble than it's worth. Does your receiver have pre-outs? You need to at least have preout for the surround channels to connect to a transmitter and that transmitter must be able to have the same frequency transmission to the wireless speakers.

No, you cannot connect your rear channels binding posts to anything else other than the speaker because that signal has already been amplified by the receiver it self. Sending it to a transmitter which doesn't have a high impedance will cause damage as the transmitter is not receiving a pre-amped signal.

If your receiver has pre-amp outs, then yes - it is possible. Just like how you could get a wireless transmitter for a subwoofer, it can work for individual speaker channels too.
Okay, so..?

Do soundbar give a true 5.1 or 7.1 surround sound?

I don't have plaster ceiling. 

The wire will be expose all the way if at the ceiling.

thats will create pleasant view