How will this rear windshield affect speakers and back lights that mount to the overhead bar that the window covers?

Hello, I assume you are referring to mounting brackets for lights and speakers.  If so, there is a small gap between the windshield and the roll bar that most smaller clamps will fit in.  If you have larger clamps then you may have to trim the windshield in order to get the clearance you need.  Simple to do with a jig saw.