How Do I Charge, and Maintain 2 New 6 Volt Batteries???

You will get more than out of 2 group 24's, yes. Just not more amp hours out than a similar sized 12v battery (24's are pretty small). The big advantage of the golf cart batteries is that they are tough and will last longer beating on them (such as deep discharging them) than many 12v batteries will.

Jim