Minecraft wiki entry for Memory, associated text: Size
"In a void", that includes required blocks supporting redstone.
Delay
The number of ticks from the trigger to switching the output.
Cycle time
How often the latch can toggle, including any recovery time. This is the period of the fastest clock that can drive it.
Other Devices
P == normal piston, SP == sticky piston, C == comparator, H == hopper, D == dropper.
Trigger
rising edge (the usual), falling edge, high or low level. Level-triggered TFFs oscillate on long pulses.