I have been using the same GPS model on motos since 2001, on dozens of different motos, I am beyond familiar with my GPS unit.
The best location for a GPS unit on a moto is within the sightline of forward traffic.. say right above the speedo/tach of the moto, because the less distance your eyes have to veer off the forward traffic, the more time you have to react to changes.
Besides the regular GPS functions, I often use the GPS to determine the entry speed to the next corner in unfamiliar terretory. GPS unit gives me more accurate speed than the speedo anyway, I often block the speedo with the GPS.
I don’t usually use the GPS to give me directions, most of the time I use the GPS to find out the general direction of my destination and head towards the destination according to my own choosing of roads. only after I get lost that I use the GPS for directon to get to my destination. I never listen/hear anything the GPS unit sounds off, bluetooth is unnecessary IMO..