1) For the height of your hands, a good rule of thumb is to have your elbows at a 90-degree angle and your wrists straight when typing or using the mouse. This will vary based on your height, so use your own measurements to find the ideal height for you.

2) Considerations for good posture at a standing desk include keeping your feet flat on the floor, engaging your core muscles, keeping your shoulders relaxed, and avoiding leaning on the desk. To avoid injury, take frequent breaks, switch between sitting and standing, and adjust your desk and chair as needed to maintain proper posture.

3) When using a keyboard at a standing desk, make sure it is at a comfortable height and angle. Use a wrist rest if needed, and consider using an ergonomic keyboard to reduce strain on your hands and wrists.

4) When standing, distribute your weight evenly between both feet and try not to lean on one side or the other. Consider using an anti-fatigue mat to reduce pressure on your feet and legs.

5) It is recommended to stand for at least two hours per day, but no more than four hours without a break. Listen to your body and take breaks as needed to avoid fatigue and strain.

6) Three books that may be useful on this subject include "Stand Up! The Workstyle Innovation Guide" by Tomohiro Tachi and Emiko Shibazaki, "The Joy of Movement: How Exercise Helps Us Find Happiness, Hope, Connection, and Courage" by Kelly McGonigal, and "Work Smarter: Live Better" by Cyril Peupion.