How does the resistance of the load affects a voltage divider?
Yes this is how it works. The load needs to have very high impedance so that it doesn't affect the voltage division. An OP buffer could be used between R2 and R4.

Perhaps using a zener diode as a voltage divider could be of use here. This picture is from the site http://www.electronics-tutorials.ws/diode/diode_7.html which explains this further.


Depending on which zener diode you're using the voltage, Vz, will (under the correct circumstances) be the same independent on the load, Rl, connected to the circuit.