First, are you a "Pond Boss" subscriber? If not, that's your first starting point. The subjects covered in PB issues mostly pertain to your stated desires and questions. Besides, PB subscriptions help support this website.

Second, you may want to obtain the book "Raising Trophy Bass", which will provide a better understanding of a healthy fishery environment.

There are no short (and accurate) answers to renovating a pond to suit ones desires. Just do your homework and learn the pros & cons of the different management options before getting underway.

Rotenone is a chemical used to kill off existing fish prior to restocking (requires a pesticide license to purchase/use). And, it would likely be best to remove the bullhead before going any further. Unfortunately, bullhead will be the last specie to give up the ghost to rotenone. So, you may want to catch and relocate any fish that you wish to keep - alive.