Firstly, you have been asking for the electrete microphone load resistor. Strictly spoken, it depends on the microphone specification. I my view, 10 k would be more reasonable for most microphones than 68 k, which is written far above in this thread. Probably both values will work. Instead of bombarding others with questions, you may want to check which value is appropriate for your microphone.
Secondly, you ask about the coil wire. Bare or silver-plated copper can work as well, if the windings are clearly separated. A short between two windings must be strictly avoided, that's why most people prefer enamelled or "magnet" wire.