About HSCS: a number of architectures are describe in a classic textbooks. The most important hint - cascode biasing works as gate follower, reproducing voltage potential at the source of biasing diode to each source of cascode devices. it means that You are able to set appropriate VDS value for current source transistors by placing a level shifter in cascode bias branch (like
here - You could play with it by replacing M34 devices with ideal DC voltage source and checks whats happens).
You have two stage opamp with cascoded first stage. Assuming 10V/V (20dB) of intrinsic mosfet gain, the opamp gain for this case is simply 3×20dB (in the first approximation)