Are there any resources besides the couple of blog posts and reading the
source?

I found this surprising:

        OCaml version 4.02.1

# #use "topfind" ;;
- : unit = ()
Findlib has been successfully loaded. Additional directives:
  #require "package";;      to load a package
  #list;;                   to list the available packages
  #camlp4o;;                to load camlp4 (standard syntax)
  #camlp4r;;                to load camlp4 (revised syntax)
  #predicates "p,q,...";;   to set these predicates
  Topfind.reset();;         to force that packages will be reloaded
  #thread;;                 to enable threads

- : unit = ()
# #require "compiler-libs.toplevel" ;;
/Users/leonidrozenberg/.opam/4.02.1/lib/ocaml/compiler-libs: added to
search path
/Users/leonidrozenberg/.opam/4.02.1/lib/ocaml/compiler-libs/ocamlcommon.cma:
loaded
/Users/leonidrozenberg/.opam/4.02.1/lib/ocaml/compiler-libs/ocamlbytecomp.cma:
loaded
/Users/leonidrozenberg/.opam/4.02.1/lib/ocaml/compiler-libs/ocamltoplevel.cma:
loaded
# let a x = x + 1 ;;
>> Fatal error: a unbound at toplevel
Fatal error: exception Misc.Fatal_error