Regarding roxygen resources, several more have since emerged, a few more have emerged, to quote my own notes:
Often when I google Roxygen or Roxygen2 I have trouble finding
documentation. Here's a compilation of some key resources:
Hadley Wickham has a great introduction to core features of Roxygen 2
There are several vignettes listed on the Cran site for Roxygen 2
RStudio has notes on running Roxygen
roxygen2 package source code on github
