What is the most efficient way to stride when you’re on a long run (60+ mins)? Should the stride be long or short? Should the feet be lifted high or remain close to the ground?

While stride length can be ascertained taking height and limb length into consideration, most regular runners tend to establish a comfortable stride length that falls within the optimal range.
A beginner typically takes short strides and runs more slowly. However, after a few training sessions the stride becomes longer and the speed increases as well.
A measure of good running technique can be gauged by the almost noiseless contact with the surface. Be it the ground or treadmill belt, if you can hear the thump, thump of your feet, you should make an effort to land more softly.
Try not to force your body into a specific stride length — it can result in an uneconomical expenditure of energy apart from upsetting form and causing injury. Run naturally, without extra effort, and you are likely to find your optimum stride length.
Secondly, a good knee lift is recommended, again one that is maintained naturally to accomodate stride length.
There are 2 ways that runners can hit the ground: With the ball of the foot (pedal style) or on the heel (stride style). Long distance runners tend to adopt the heel posture for bio-mechanical reasons.

I am a 26 year-old guy weighing 63kg. One year back my ankle got twisted while playing Volleyball. An X-ray revealed no bone injury, just a sprain. I was given medication and told to take rest. But I still have a problem with the ankle which swells when I walk or stand for a long period. Currently my weight is 79 kg. Please suggest some treatment/therapy or any exercise which can offer complete recovery from the injury.
Your injury appears to be a rupture of one of the ligaments around the ankle. Most of these injuries heal with medication and physiotherapy. Your trauma seems to be compounded by your unexplained weight gain of 16 kg in one year. You need to shed weight with a good diet and exercise plan. The ankle needs to be braced and muscles strengthened with physiotherapy. If the problem continues you may need an MRI and an orthopedic consultation.
1. Your increase in weight by 16 kg has clearly aggravated your ankle problem, which now has to bear the extra load. You must get back in shape with diet control, since exercise has been limited.
2. People tend to treat sprains as minor problems and neglect them, hence the pain persists. A plaster cast for 3 weeks would have helped the ligament heal well. Have strain X-rays of the ankle or an MRI scan done. An unhealed ligament injury will need surgery.
3. Corrective footwear with a W wedge sole along the outer third of the entire length of the shoe should be worn for 3 months.