The voltage rating on the capacitors is probably on the other side of the capacitors, when you take them out you wilkl be able to read it - but just measure the voltage across the capacitors, and pick the next highest voltage available.
As for the resistor, you need to consult the circuit, as it's 'burnt up' and the remaining colours probably are nothing like they should be.
Is there something wrong with the amp?, a blanket change of the capacitors is probably pointless?.