Steve P great questions. It's perfectly fine to say the mantras out loud but they are considered more potent and a form of meditation when said internally. You are imprinting on the mind the energy quality of that particular mantra. And yes sometimes the malas can be a little mechanical and awkward but just keep going with it and this will change with practice!
Today, the mantra brought in a gathering of great Minds. Since I am a Catholic, I first noticed Jesus. I was invited into the mass group. All were there but we were all alone in our mantra. We became triangles. Gathered my thought and went back into the mantra