How do I safely power 2m 144 LED/m WS2812B strip with 5v and 10a?
Thin wire you can not solder to  PCB strip. If you planning high brightness, few wires should be used in parallel. AWG22 is big enough. If max current 7A, power wires should be connected both side and  in middle.
Power wires going from supply, from MCU board only data, you may not connect power. But make sure grounds of board and strip connected.
One side of strip connector is signal input plus power, second to connect next strip input usually female, but check the strip side where wires soldered, should be marked IN.