When the Doctor identifies himself as "Dr. James McCrimmon," he is referring to one of the travelling companions from the 2nd Doctor/Patrick Troughton era of the original series. Specifically, young Jamie McCrimmon, a veteran of "the Forty-five" (as in, Scotland's Second Jacobite Rebellion of 1745). He returned to Scotland after the "War Games" story arc (in which the Time Lords of Gallifrey were first introduced).
As for the "Dr. Bell" the current Doctor mentions having studied under? That's most likely the same one whose remarkable talent for diagnosis inspired a former medical student, named Arthur Conan Doyle, to model a certain consulting detective after him.