I know this is late but...
If you can't sit in a full squat, with your heels on the floor naturally, your begging for an achilles tear, besides putting pressure on your knees. It's a CLEAR sign you got tight calves and achilles tendons, which is forcing you forward and sets you up for eventually injury. As far as after surgery, it's naturally going to feel harder because of scar tissue, but that can be remedied.
You have got to stretch them before sports and general activity, otherwise setting yourself for what just happened. Many of the calve stretches are useless, such as pushing against a wall with your feet behind you. Just do 'downward dog' everyday, and if you don't know what it is, just google it. It's not the fact that it's yoga, but the fact that it gives you a great stretch all the way up your legs, calves, hamstrings, achilles, feet, without putting pressure on your lower back. Pushing your hips backwards and trying to touch your heels to the ground will increase the stretch. Make sure your feet are pointed straight and parallel, otherwise you lose the stretch.
You should test your achilles by the full squat, with your ability to keep your heels on the ground.
As far as strengthening, calf raises work and again, when doing things like squats keep feet flat on the ground. As far as calf raises, you need to start doing them with one leg and eyes close to help prio-perception as recovery. If you don't move, you can't accelerate healing and everything eventually tightens and muscles weaken.
Google Dr. Jolie Bookspan.. She's the only person I swear on...
http://www.amazon.com/Your-Pain-Without-Drugs-Surgery/dp/1585189847
