The State Ports Authority's Wando River terminal is also in Mount Pleasant. Charleston is the largest city near Mount Pleasant, although Mount Pleasant is quite large in its own right. Here is a map of the Charleston area.
Group means battery physical size, ie group 24 and group 27 as mentioned earlier. Its CCA/MCA rating that counts. I have two batteries, one is 1000 cca's the other is 600 cca's (cold cranking Amps). The 1000 is the starter battery, the 600 runs accessories and is a back up starter. The higher the CCA rating, the more starting power you have. This is oversimplifying it but it gives you an idea of what a battery rating means.
reference group. a group with which an individual identifies and whose values the individual accepts as guiding principles.