I read the Maxwell Staniforth translation (Penguin Great Ideas). It felt comfy to me because I was used to 20th century prose. For a more modern translation, Gregory Hays (Modern Library) is generally considered the best.
You have to understand that no book can impart confidence or any other positive trait by itself. What it can do, though, is nudge you towards the right direction; towards the path of introspection and self-awareness and broadening your horizons. Confidence, for instance, stems from knowing that you have put in the hard work to git gud at a specific task and are capable of reproducing it and achieving others as well. Meditations will certainly help you realise that and much more, but how you implement the knowledge given in it is what will ultimately decide how much your life improves.
So yes, it will help, but reading it is just the first step. Take it.