Using the same lights for running lights, blinkers and brakes can get I little complicated. You can do it with a flasher and double throw switch but it's a little complicated.
LEDs should only affect the blinking speed of the flasher. A load resistor is fine for this.
Running lights(low watt) tied to the lights. Brake lights(high watt) to the pedal. 1157 type bulb. I hope that makes some sense. http://www.how-to-build-hotrods.com/turn-signals.html
. See the first diagram.