Does an increased reproduction/mortality rate provide an evolutionary advantage?
The first part of the question is interesting.


  Does an increased reproduction/mortality rate provide an evolutionary advantage?


The concept of evolutionary advantage for a species needs to be used with much cautious as different definition of evolutionary advantage may exist. You should typically have a look at game theory beforehand to understand the issue of definition.

A species that have shorter generation time tend to respond faster to new selection pressure (even more so in species that have short generation time and also have high population size).


  why has humanity not been enslaved by mouse¹ overlords with superior intelligence and adaptations to suit the environment perfectly?


You seem to be viewing intelligence and/or species competitive ability as end goal of natural selection which suggests important misunderstanding of how evolution works.


  One of the reasons these traits may be more harmful than helpful is that predators benefit from a population increase


You might want to have a look at the post What prevents predator overpopulation?