1. You seem very concerned about injury. Properly performed jelqing for a reasonable period of time and stretching that's done with moderate levels of intensity should both be fine for a beginner. Injury is invited when a PE'er tries an advanced exercise too early or with too high a volume or intensity; when jelqing or stretching is done at a significantly higher intensity; or when insufficient rest is taken between sessions.
Just look out for anything obvious such as constant turtling, any sort of pain, visible bruising or discoloration, lower EQ, etc.
2. Definitely switch hands. You can observe the angles and grip that your dominant hand naturally makes, and try to replicate that with your non-dexterous hand. Try to get the two hands to work as similarly as possible.
Just look out for anything obvious such as constant turtling, any sort of pain, visible bruising or discoloration, lower EQ, etc.
2. Definitely switch hands. You can observe the angles and grip that your dominant hand naturally makes, and try to replicate that with your non-dexterous hand. Try to get the two hands to work as similarly as possible.

