I do not have my family cage in right now to look at, but do these mount to the top of the roll bar at the corner, and will these work under a Bimini top for the family cage?

Yes, usually at, or near the corners. We will typically drill and tap the cage tube, to accept a bolt. Yes, they can be used under or with any top, and should have plenty of clearance. You are also free to put them where they best suit your needs.