Opamp BJT mixed circuit analysis
The schematic of the problem does not match the schematic of the solution. I am not sure there is a general approach to such situations. 

Anyway, start off by assuming the op-amps are in balance and the transistors in active mode. That means the inverting and non-inverting inputs are at the same potential and the transistors have Vbe of about 0.7V and Vce > Vce(sat). Ignore base currents in most cases, especially if the problem does not give you hFE, since you will have no way to calculate them in the latter case. 

Then try to solve the equations with the tools you know- series/parallel combination of resistances, KCL, KVL. 

They ask about an edge case, from the function of creating a constant current at the output we can see that the effect of increasing the value of RL is to decrease Vce of Q2. When Vce of Q2 is equal to Vce(sat), RL can no longer be increased without greatly changing the current- so you can solve for the value of RL when Vce is exactly equal to Vce(sat). That's the 2nd part of the problem.