As a Lund dealer, there are 5 hinges across the bench with three screws in each. Repeated removal will definately reduce the holding strength. When trolling for increased floor space, flip the bench up for additional seating.
Reserve Cranking Amps are the critical deep cycle criteria. The larger the number the better performance. Additionally, most of the issues that shorten battery life revolves around improper recharging techniques. Car chargers and 12 volts are not the best for long life.