The way he has me doing heel drops is to go down slowly on one foot and then use both feet to go back up to your toes: http://www.sportsinjuryclinic.net/rehabilitation-e...
I've progressed to holding a 10lb weight while I do it. He told me not to worry about trying to balance but to hold on to something. I have a step by my kitchen counter that I use but a staircase with a railing is also good.
At the sessions the PT does some calf massage and also uses this metal thing to scrape along the muscles and tendon to try to break up small scar tissue (I think). You could mimic with foam rolling your calves I expect.
He gave me some calf stretches but I'm fairly flexible so they don't do much.
The other thing he is having me do is some hip strengthening things. He thinks I may use my feet and ankles more than necessary because of not being strong enough in the hips: bridges, clam shells and something called "side lying hip abduction" - all of them with a theraband around my legs just above the knees. (The last one is really hard.) These I just hold for a minute.