If you're powering the Arduino through Vin you need to provide at least 7V. If the V+ from the speed controller supplies a regulated 5V then you could connect it directly to the Arduino 5V line and power it like that.
Using the Servo library, I suggest you use write(angle) rather than writeMicroseconds(microseconds).
I didn't realise that the forum's alignment codes would affect stuff in [ code ] blocks too but it seems to, so it would probably be best to make sure any code you post is left aligned in future - the center alignment doesn't work at all well for code.