The 0.7 VRMS is the amount of AC signal applied to the input of the amplifier to give you full output - 100 Watts into 4 ohms in this case. The bias in this circuit is used to set the crossover point at which the PNP and NPN output transistors conduct. If they conduct at the same time, there will be current draw with no input signal and they will destroy one another. If they conduct too far apart, you will have a distorted sine wave. To adjust, apply a minimal amplitude sine wave (maybe 0.1 VRMS) at say 1 Khz to the input and adjust the bias until there is no space between the positive and negative peaks of the output signal.
I would recommend using a reduced power supply voltage (using a variable transformer), or at least insert very small fuses in series with the both the positive and negative supplies. If the bias is too far off, the output transistors will destroy themselves in milliseconds! And don't forget to load the output with a 4 ohm load. Output transistors don't like open circuits.