Path integrals for the relativistic particle: Some conceptual and pedagogical comments

In my textbook on Quantum Field Theory \cite{tpqft} and in a recent paper \cite{tpejc2018}, I advocated a lattice regularization procedure for defining the path integral for the relativistic particle, using the non-quadratic action containing a square root. I also provided an interpretation of this result in terms of the Jacobi action principle. This note clarifies several conceptual and pedagogical issues related to this approach and highlights some interesting open questions which this result leads to.