I have a question about Botox for frown lines.

Lately, I've been increasingly concerned about the wrinkles between my eyebrows, so I'm considering getting Botox. Since it's my first time, I have many questions. I'd like to know how painful the procedure is—is it generally quite painful? Also, I want to know if a single injection is effective or if I need several to maintain a natural look. Furthermore, I'm curious how long the effects typically last and if the results return to normal over time. I also have a very faint surgical scar on my forehead; I'm wondering if this will cause any issues. As a first-timer, I'm worried and hesitant because I'm afraid it might look awkward. If anyone has actually had this done or knows a lot about this, please share your experiences or advice.