As for #2, I'll have a more analytical stab at it:
In both cases, total lift generated will decrease by the same amount as a climb is initiated. L = W*cos(climb angle), no speed dependency.
Parasite drag will essentially remain the same and can thus be ignored in this context.
As for induced drag,
L = S * rho/2 * V^2 * C_L
or, solving for the lift coefficient,
C_L = L/(S * rho/2 * V^2) = k1*L/V^2 (k1 is a constant)
The induced drag coefficient is proportional to the lift coefficient C_L squared,
CDi = k2 * C_L^2 = k2 * k1^2 * L^2 /V^4 = k3* L^2/V^4
(Induced drag is proportional to the induced drag coefficient)
The rate of change of the induced drag coefficient as the lift changes is calculated,
dCDi/dL = 2 * k3 * L / V^4
We see that V^4 remains. Conclusion: The rate of change of the induced speed as the amount of lift generated changes is highly dependant upon the true airspeed. The amount of change of total drag as you enter a climb is very unlikely to be the same at M.67 and M.8. At a high speed, the change in induced drag will be a lot smaller than at low speed.
It's late(ish). If I messed something up I'm sure I will be corrected.
