Why do we need 4 resistors for a common emitter amplifier?
RL is not required to bias the transistor collector current, however without RL you will get zero output, since the output would be connected directly to Vcc if RL is replaced by a short.
Typically you want to make RL as high as possible to maximize the voltage gain, but not so high that the output clips high or low with extremes of input voltage and taking bias tolerances into account. That means that RL is usually selected so that the collector voltage (with no input) is more than half of Vcc.