Do you run conventional or command?
Unless you want to attempt to control the markers, I just use track voltage.
For the flickering firebox, I buy the LED tea candles from a Dollar Store and remove the flickering LED, cheapest source I've found. They work great for the firebox, gives you the flickering effect for no effort, just a diode, capacitor, and a resistor from track power. You can power the classification LED's the same way.
A 1N4003 diode, a 220uf 35V capacitor, and a 1K resistor will power the flickering firebox LED. Use a second 1K resistor from the same diode/capacitor filter for the classification lights, wire them in series.
