lightweight, inexpensive speed controllers

[yash101]

Are you programming this yourself? If so, it will be complicated because I am implying that you have no flying experience. You might try a KK board controlling the copter, being controlled by the Arduino. The KK board will stabilize the quad and do all the important functions. The Arduino can be the controller. You may wind that easier. How much experience do you have in Arduino programming? I would use something like the Propeller chip because you can code the multicore environment to do the flight controlling in a core, and the rest of the stuff in another! However, this all is based on what MCU you are most experienced in using!

Also, using a linear voltage regulator at those currents would cause the magic smoke of death to puff out of the regulator. Powering my RasPi from an LDO gets the chip so hot, I have it connected to the aluminum chassey of the robot for a ginormous heat sink!