Superted,
Those graphs you refer to are pretty good but you must remember their limitations.
The thing to remember is that they are for the Interantional Standard Atmosphere where there are no inversions and no isothermal layers (below 36000 ft).
If a question asks about climbing or descending through an isothermal layer just use the graph indicating flight above the tropopause (Where in the ISA is all one big isothermal layer).
If it asks about an inversion just remember that the effects of changing pressure with changing altitude are the ones that affect the density most. So climbing through an inversion still causes density to decrease. Whenever density decreases the ratio of TAS to (CAS,RAS,IAS,or EAS) increases. An inversion does not change this effect.
The trick with an inversion is to remember that it is temperature that controls the TAS : mach number relationship. An inversion revereses the normal temperature lapse rate so you must reverse the effets on the TAS : mach number relationship. So (in an exam question) climbing through an inversion at any given TAS causes mach number decrease. when descending through one at constant TAS the mach number increases.