problem in finding effective resistance
Think of R1,R3 as forming a Thevenin source, and R2,R4 a separate Thevenin source.  Now Rl is merely connecting between two Thevenin sources, so the current thru it is easy to determine.  With that you can compute the loaded voltage of the two Thevenin sources, which then pretty much tells you everything else.

That's just one way.  There are various ways to eventually get all the voltages and currents in this circuit.