For the question you didn't answer yourself: given the increased experience from opponents in FoV, the relatively low cost of the mindreads that don't give skill/stat points or spell levels (which there are plenty of) would not incur a significant extra debt. Theoretically you are better off skipping the 'useless' mindreads, but practically it isn't going to make much difference (I avoided or reloaded for a lot of the useless mindreads in D2:ED and mindread everyone in DKS).
Opponents respawn in the caves and sewers, as well as in the Crow's Nest, once you've gotten to that part of the city (until you've completed a certain quest there). You can easily make up any mindreading debt without specifically grinding, but you have the option to go through one or more caves again, if you wish.
Alternately, if you have the skill points to spare, level 15 of the Mindread skill reduces the cost to zero.
