Audio Amplifier Design Questions
C1 is a DC blocking (coupling) cap exactly as you suspected.
R1 is to provide a DC path for the bias current for the input stage of the op-amp.
The gain will (1+R2/Rpot) with a negligible error due to finite open loop gain of the amplifier.
1+10000/Rpot = 150, so Rpot = 68.1 ohms. A=146.8 which is within 5% of 150.


Note that typical gain-bandwidth for this amplifier is 3MHz, meaning your typical closed-loop bandwidth for this amp will be 20KHz. Likely fine for an AM receiver.