1. Yes, but the Vajroli Mudra is more powerful when combined with the sacred rites.
2. An erection is not necessary for transmutation, only concentration, remembrance, prayer, imagination, chastity, and faith.
3. It means you have found a gift. Some people respond better to certain practices than others. Now that you know one that prevents you from falling, hold true to it with a discipline of steel.
For thirty years I sought God. But when I looked carefully I found that in reality God was the seeker and I the sought. -Bayazid al-Bastami