heartbeat monitoring
OH PLEASE!!!
Of course you should have a safety system in place especially with something with a spinning blade but you, me and the OP know that such a device would cause more harm then good (false readings, complicated implementation).
(because with relays you can't really control the speed of the motor);
This is false.
I have PWM'd relays to control motor speed.
It works ok but its noisy and the speed control is alittle rough.
Other then these, the advice is sound.
FWIW Sending video over wireless with arduino sounds challenging.