yeah lunges are <difficult>, no matter how your knees are doing. I really have to be in the mood. so for calf muscles, I've found that seated calf raises are a HUGE help. when you raise up onto the balls of your feet, hold it for a long moment, and then come down. make sure not to overextend when you're flexing on the way down. a tendon pull will really set you back
also, tying a weighted plate around your hips w/ one of those belts and then standing on a platform for calf raises can be great. or simply hold the weight in one hand.
for thighs....well....if lunges are out, and squats hurt, I'd say aim for the seated leg extension machine. those definitely yield results.
basically, genetics seem to play a huge role in muscle development, but I think cardio also plays a huge role in results when used in conjunction with whatever weight training program you're doing.
exercises referred to as "good mornings"? probably something like a warm up....or something really painful lol...that'd be my guess. I have no clue.
yeah seems painful hahaha ^^