A switching power supply just describes how the power supply regulates power. Switching supplies are used in lots of electronics, so nothing overly special about the charger.
Many power regulators step the voltage down by throwing the excess voltage away as heat, obviously not very efficient. A switching supply switches on and off quickly, regulating the power output that way. It's more efficient than heat-dissipation voltage regulators.
Current generation NiMH batteries should not have any memory effect, and can be recharged at any time (ie: they don't have to be fully run-down). However, they're not optimal for stand-by devices like flashlights since they lose about 1% of their capacity daily when in stand-by.
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